User Interface?

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#1
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Just doing a bit of "brain-storming", here.

 

I've been searching, just a bit, for some kind of user interface for my next generation accelerometer. Selection criteria include:

 

1. Presents a simple "menu" and provides a way for the operator to navigate the menu and select menu choices. This is THE top level criterion.

 

2. Battery power. It can take some current (10's of mA when on) but it needs to be really low current (<1uA?) when off/idle/disabled. Second level criterion.

 

3. It needs to be able to withstand a variety of moderately severe weather conditions (IP65, probably) OR be mounted in a way that protects it from weather (while allowing operator select operations). Second level criterion.

 

4. Moderate cost or lower (thinking of a single quantity upper limit in the $10-$15 USD range). Second level criterion.

 

5. Maximum length 3.0"//77mm. Second level criterion.

 

6. Does not require extensive machining operations on enclosure. Third level criterion.

 

7. Readable in near-full sunlight. Third level criterion.

 

8. Characters/symbols large enough that vision assistance is not needed. Third level criterion.

 

9. Maybe not full pixel-accessible? Lines of characters are probably adequate. Third level criterion.

 

10. If a display, it can be monochrome. Third level criterion.

 

I was going to list some of the ideas I've had, but rather than limit the idea "flow", I'll leave this empty and let all of you weigh in with your suggestions, concepts, ideas, catalog numbers, what-ever.

 

Have at it!

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Last Edited: Wed. Aug 14, 2019 - 08:31 PM
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ka7ehk wrote:
1. Presents a simple "menu" and provides a way for the operator to navigate the menu and select menu choices. This is THE top level criterion.
Android or a web browser

 

Monday morning - the original natural gas meter was replaced with a WSN version.

Asked of the technician the meter's battery voltage.

She placed a small plastic box on top of the plastic portion of the meter (meter is aluminum, mechatronics in a probably polycarbonate enclosure with an internal long-life battery) and read the data on what appeared to be an industrial Android phablet.

Answer "25dBm"

laugh

(she knows!)

That's an excellent ERP to a tower about 10km distant.

She was reading near reams amount of data and was interacting with the software on her handheld device.

Never did get an answer to my question.

Am assuming the small plastic box contained a magnet to enable CBIT or Bluetooth 4.

 

Some Bluetooth 4 or 5 modules have a PA to reach an ideal 1km, some adding mesh to increase the network's range, and some have a transparent UART to replace Bluetooth 2 and 3's SPP.

LoRa's range is an order of magnitude greater than 1km with an application network (client-server, operator interface is a web browser)

WebUSB is an interface between a MCU and a web browser (Chrome, Chromium, Opera) (demo MCU are tiny85, mega32U4, and SAM D51)

 


WSN - Wireless Sensor Network

phablet - in-between a smart phone and a tablet

CBIT - Commanded Built-In-Test

PA - Power Amplifier

Qualified Mesh Products | Bluetooth Technology Website

SPP - Serial Port Profile

 

ATtiny85 - 8-bit AVR Microcontrollers

ATmega32U4 - 8-bit AVR Microcontrollers

ATSAMD51J19A - 32-Bit SAM Microcontrollers

Examples | Building a Device for WebUSB  |  Web Fundamentals  |  Google Developers

Browser compatibility | USB - Web APIs | MDN

Tiny USB

WebUSB is here! TinyUSB now has WebUSB support at Adafruit! - YouTube (6m39s)

WebUSB - Microsoft MakeCode (micro:bit)

 

P.S.

IMT-1–Tablet–ADLINK

if such is too expensive then some tablets and Chromebooks are near sunlight-readable though with marginal display protection.

One way to harden a display's cover glass :

cellhelmet Liquid Glass Screen Protection | RadioShack

 

"Dare to be naïve." - Buckminster Fuller

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Now, there is an option I had not previously considered! Thanks! Maybe NFC would  work for that?

 

Jim

 

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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You're welcome.

ka7ehk wrote:
Maybe NFC would  work for that?
Yes though extremely short range (much less than the width of a typical desk or the height of a tree); don't know NFC''s current consumption.

 

"Dare to be naïve." - Buckminster Fuller

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Was thinking of something put  up next to the  enclosure.  Already using reed switches and magnets in a couple of places to activate things without opening the box. This would be another place where that same technique might be used.

 

By "user interface", I was originally thinking of something built into the device that the user would have to touch, read, etc, to operate. This actually moves that outside the weather resistant box. 

 

Currently, the user has to open the box and attach a USB terminal device to configure it. I was hoping to make that more streamlined so that bulky technology did not have to be carried into the field.

 

Thanks

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Last Edited: Thu. Aug 15, 2019 - 01:23 AM
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ka7ehk wrote:
This actually moves that outside the weather resistant box.
There are IP67 USB connectors and that IP54 tablet might meet your requirements though the customer or operator may balk at the tablet's price and cost.

wrt the operator, Bluetooth 4 or 5 might be easier; can mount a Bluetooth module and magnet onto the top end of a pruning stick (better is a painter's hollow aluminum extendable pole) with the operator's interface mounted on their tool belt.

Microchip RN4871/RN4870/BM71/BM70 are 10Kbps max; TI Bluetooth 4 may reach or exceed 100Kbps.

 

edit :

http://www.ti.com/wireless-connectivity/simplelink-solutions/bluetooth-low-energy/products.html#p3098=8051 (Bluetooth 4 with 8051)

These are in the inexpensive Bluetooth 4 modules by the ones of China though customization requires IAR Embedded Workbench.

Realtek (Taiwan) Bluetooth SoC may be more open and code may be FOSS.

Bluetooth - REALTEK

 

On the operator's tool belt could be

ezLCD-313 - Indoor/Outdoor, Sunlight Readable, 3.5" Smart LCD | Earth LCD

Microchip PIC24 with LCD

Microchip has LCD code with graphics stack if want to roll-your-own.

 

PDA has similar though smaller with an XMEGA (code's in ASF3); don't know if that's bright enough for daylight sunlight :

Precision Design Associates - 28xx Series - TM2801

 

edit2 : strikethru

 

"Dare to be naïve." - Buckminster Fuller

Last Edited: Thu. Aug 15, 2019 - 01:58 AM
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You could bluetooth down to a phone..though need some way to turn it on (don't want the "hello" detector to use up a bunch of power (even at a microscopic rate) 30.999 days of the month waiting around for something to happen).

Maybe use a phone camera flash to trip a photodiode into waking things up for 30seconds.  

 

However, from the initial question, it appears the unit will be in the operators hands at the time of setup--correct?   That scenario could avoid bluetooth & just use a data cable to the phone (use a waterproof usb jack).

 

A phone has the advantage that you need worry somewhat less about freezing weather affecting an LCD (if important).  It also requires no switches (which require sealing & expense).   If you were to use a membrane keypad, Bergquist makes the best for outdoor apps.

 

Maybe a std char display would be fine---throw a switch when done looking at it--perhaps use tristate drivers to fully disconnect it when not in use. 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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avrcandies wrote:
... about freezing weather affecting an LCD ...
OLED is -40C..70C though not sunlight-readable (would need a sunshade)

OLED - Newhaven Display

 

"Dare to be naïve." - Buckminster Fuller

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OLED is -40C..70C

That is big progress compared to some cheapie character modules---get them well below freezing & some brands can become like molasses.   

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Folks, I am going to start a separate thread about NFC, just because I want to know  more. Please keep the ideas coming, here.

 

My original concept for this "user interface" was simply to have something smaller, and easier to use than having to open the lid of a weather resistant enclosure to configure it through a USB cable and terminal  device. The goal was NOT data recovery, but management. Now, I recognize that some technologies can or might do both. But, my first idea was something equivalent to a display and keypad for config, only. 

 

Thanks to several suggestions, it has become apparent that my original idea was pretty limited. To a large degree, that is EXACTLY why I started this thread: to help break out of the limits of my first idea(s). That particular barrier has been pretty much  shattered. Now, with your help, lets continue exploring some of the alternatives. 

 

Many thanks and keep the ideas flowing. This is great!

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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I read #1 and my first thought was "e-ink". YMMV.

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My first thought was AVR Butterfly!  LCD, joystick, menu system all in one.

Jim

 

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You could use RFID, that has a larger distance than NFC. You could also see if you could use touch keypad. That can also be used in a closed kabinet.

Other thing might be a infrared remote, but that might prove costly current wise.

 

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Must admit I was down in the weeds with a 20x2 LCD display and a few pushbuttons.  I don't think the specifications called for "... and the user must have the relevant app installed on their smartphone what they brought with them.".  For #7, build a little plastic sunshade.  For #8 - How large is large enough?  Poor spec, that.  S.

 

Edited to add:  Putting it in a weatherproof box is left to the production engineers.  See membrane keypads if you're worried about the pushbuttons.  S.

Last Edited: Thu. Aug 15, 2019 - 01:42 PM
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with M8 IP67 circular connectors and off-the-shelf cables; case cutouts are anti-rotation and can be done by a local machinist.

Its mega169V can be updated to recent megaAVR to add either QTouch or a PTC peripheral; joystick replaced by a D-pad in cap touch sensors.

An AVR Butterfly can be reasonably ruggedized by the same method used for smart phones (conformal-like spray-on coating)

One may have already created a 3D printer file for an AVR Butterfly enclosure on some CAD web site.

If entering into medium-rate production, an existing prototype case eases creation of the injection molds for production cases (likely a two piece snap shell)

 

AVR Butterfly

AVR Butterfly - Microchip webdoc

Brad Connectors - Molex | Mouser

 

edit :

Water Repellent Spray Applications | Anti-Wetting (NeverWet)

 

"Dare to be naïve." - Buckminster Fuller

Last Edited: Thu. Aug 15, 2019 - 03:03 PM
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likely a two piece snap shell)

If mounting in a tree, more likely a bud box style, polycarbonate UV-rated with screw-on lid & o-ring. 

 

 

The biggest question is, does this need to be adjusted in-hand, or from a few meters away?

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Snap shell enclosure for a water resistant AVR Butterfly.

Jim's existing enclosure would have an added cutout to interface the AVR Butterfly.

The very off-the-shelf NeverWet isn't UV-resistant (IIRC becomes a white powder); industrial two-part NeverWet is UV-resistant.

avrcandies wrote:
The biggest question is, does this need to be adjusted in-hand, or from a few meters away?
There may be a safety standard for operators which then links to a requirement that Jim creates.

 

"Dare to be naïve." - Buckminster Fuller

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off-the-shelf NeverWet isn't UV-resistant (IIRC becomes a white powder);

ABS is sometimes maintained/restored in the field using sandpaper ...removing the surface micro-cracks rolls back the degradation.  I seem to remember the phone company equipping their techs with sandpaper for this purpose.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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avrcandies wrote:

If mounting in a tree, more likely a bud box style, polycarbonate UV-rated with screw-on lid & o-ring. 

Curious, that image is of an IP67 rated connector:

https://www.ebay.ca/itm/Waterproof-USB-2-0-Connector-IP67-Weatherproof-Panel-Mount/322467764548

 

Unclear if cap needs to be installed for rated behaviour.  Beware the forgetful user.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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Current configuration mode is USB and a COM terminal device. So, it is not  currently "contact" but contact is required to open the lid and plug the USB cable.  The anticipated configuration process is to make the settings and set the RTC before the device is installed. There is a reed-switch and a "magic wand" that is used to start and stop recording without having the enclosure open; this is most likely done after it is installed in its measuring location. 

 

I was initially looking for something that would eliminate the need to open the box. I had  first considered a display and keypad, but that is expensive, especially when weather resistance is considered. Then gchapman suggested something that brought to mind NFC and a smartphone app; requires close but don't have to open the box. BlueTooth is another possibility but I am concerned about power consumption AND I have never been thrilled with the connection process. WiFi appears too complex for this application. 

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Last Edited: Thu. Aug 15, 2019 - 04:35 PM
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What about Zigbee?  Easy to use.  Just 4 wires to power, ground, Rx, and Tx.  Dont think it works with a phone.

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Hmmm.... (mind churning a bit, here)

 

Attraction of NFC, BlueTooth, or WiFi is the possibility of implementing the user interface as a "desktop" graphical interface and avoiding displays, keypads, and such built into the device. Have not heard of any smart devices (tablet, phone, etc) with Zigbee. This  would require the equivalent of a Zigbee "tablet", I think, or, at the very least, a ZigThing with a display and a  keypad. Thats a bit more than I would like to get into but worth keeping in the Archive Of Ideas.

 

Thanks for the suggestion!

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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ka7ehk wrote:
BlueTooth is another possibility but I am concerned about power consumption AND I have never been thrilled with the connection process.

Add a button to activate the Bluetooth? After all it's only(?) Needed sometimes. Your smartphone will automatically connect to the device via Bluetooth everytime once it have been paired when making the first connection.

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I sent a reply from my phone, but I think it got lost in the either.  Zigbee is just a simple radio.  It connects to UART on the mega.  On the other end you need a USB - serial converter to connect the Zigbee module to a laptop or tablet.  I use PuTTY to talk to the module after finding the COM port my windows machine chose for the USB-serial converter.  Then everything would be enclosed, although if your enclosure is metal it will be a problem.   I use these little boards for USB-serial:

 

https://www.amazon.com/jim-sh-Micro1v8-2-Pack-Serial-Adapter/dp/B076B9YRMP/ref=sr_1_1?keywords=microFTX+jimsh&qid=1565906357&s=gateway&sr=8-1

 

I've known the guy that makes them for a while.  They are nice little boards, if a little pricey.  Or you can make your own for cheap with a CH340 chip or the more expensive FTDI chip.

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It seems if this is mainly a one-time use, that simply adding a connector & cabling to your phone offers a few advantages:

 

The cost is very low.

The power usage impact is zero.  In fact, it could be used to provide charging to the unit (if rechargeable).

You can make a graphical app as fancy as desired.  Could be a visual app , that acts like a terminal---rather than typing, you are touching buttons, moving sliders, etc to send serial adjustments.

No need to determine "which" unit is being spoken to  (RF setup may have multiple units competing in the vicinity) 

 

Downside:

Unit must be immediately local to the user.

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Well, for low cost and weather proof I was thinking of an LED and a photodiode mounted on the PCB.

IIRC your box has a clear lid.

 

Your data connection on the outside would likewise have an LED and a photodiode, and you would use an optical serial data link, bidirectional, for your comm's.

 

If needed, you could mount the external LED and Photodiode inside a "box lid", that the User slide over your box.

It would both block out ambient light, and align the two pairs of LEDs and Photodiodes.

 

If the box was on the end of a pole, they could re-configure or read the data logger from the ground.

 

If needed you could add yet one more reed switch, to tell when the external communicator was present.

One would then not need to periodically read the photodiode.

 

With the external device forming a sun shield, one could use rather low current levels for the data transmission LED.

The photodiode need only be the clear plastic lid's thickness from the LED.

So you should have a great optical S/N ratio with low current levels, and the data rate can be as fast as the photodiode's limit.

 

JC 

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Oh, Doc!

 

That is a cool idea. 

 

Config rarely has to be done IN a tree. It is usually done well before installation. So, the pole, etc, does not help much. BUT, I DO like the idea. A little smart-phone adaptor could be very chee inexpensive. I think that standby power consumption could be made quite low. Cost is low. 

 

I do like that!

 

Not closing the discussion, of course, but you-all have made some really great suggestions and comments. 

 

Keep the juices flowing. Maybe someone will come up with an idea that is even more cool?

 

Cheers and thanks,

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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The precursor to e-ink is Sharp Memory LCD though doesn't meet the less than 1 micro-amp requirement (small Memory LCD are approx 2 micro-amp)

Adafruit's Memory LCD module has code; other code exists.

The Memory LCD protocol is relatively simple so can roll your own code.

Could create a Memory LCD driver that's compatible with ASF3 then could have ASF3's graphics stack.

 

Products - Sharp - Memory LCD

Adafruit SHARP Memory Display Breakout - 1.3 168x144 Monochrome ID: 3502 - $24.95 : Adafruit Industries, Unique & fun DIY electronics and kits

https://github.com/ganzziani/Xproto-Watch-Bootloader/blob/master/GccBoardProject1/src/display.h (GPLv3)

another module though for MSP430TM :

BOOSTXL-SHARP128 BoosterPack Plug-in Module - TI | Mouser

ASF-GFX | ASF Source Code Documentation

 

"Dare to be naïve." - Buckminster Fuller

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ka7ehk wrote:
BlueTooth is another possibility but I am concerned about power consumption ...
Bluetooth 4 and sub is coin cell compatible and is approaching the super-capacitor range.

ka7ehk wrote:
... AND I have never been thrilled with the connection process.
Bluetooth connection intervals are configurable though does have an impact on current consumption (would need your reed switch solution)

 


Apollo Ultra-Low Power MCU (Ambiq Micro)

SparkFun Artemis Module - Engineering Version - WRL-15376 - SparkFun Electronics

Artemis Module - Engineering Version - SparkFun | Mouser

 

"Dare to be naïve." - Buckminster Fuller

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An alternative to Zigbee is Atmel Lightweight Mesh on an RF megaAVR though there are qualified Bluetooth mesh modules as another alternative.

 

https://www.microchip.com/wwwproducts/en/ATmega256RFR2

[expand Documents]

...

[AVR2130]

[AVR2131]

...

[Lightweight Mesh software stack zip file]

...

Qualified Mesh Products | Bluetooth Technology Website

 

"Dare to be naïve." - Buckminster Fuller

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avrcandies wrote:
Could be a visual app , that acts like a terminal---rather than typing, you are touching buttons, moving sliders, etc to send serial adjustments.
by MIT App Inventor if one doesn't want to learn Android and Android Studio; IIRC, App Inventor has a Bluetooth 4 interface.

 

About Us | Explore MIT App Inventor

http://www.martyncurrey.com/bluetooth-control-panel/#comment-6669

 

"Dare to be naïve." - Buckminster Fuller

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Thanks for that link about MIT App Inventor and the BT Control Panel. Worth at least a study.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Following up on DocJC's optical link idea ....

 

Just took a look at IR transceivers at Mouser. A little spendy ($4.75 to $5.75) but they have some positive attributes.

 

I do not understand one of the characteristics, however. These all seem to be designed for IRDA. Here is a typical spec sheet:

 

https://www.mouser.com/datasheet...

 

They say 9.6 kbits/second to 115.2 kbits per second. But, then, under Pin Descriptions it says:

Receiver output. Normally high, goes low for a defined pulse duration with the rising edge of the optical input signal.

Then, in the Receiver characteristics section, it says:

RXD pulse width of output signal, 50 %;  Input pulse width=1.63 μs; 1.7us min; 2us typical; 2.9us max

So, its not clear to me whether the output pulse width varies with the input pulse width. The 1.63us pulse width would appear to correspond to 613 kbit/second (which seems odd, given the max 115.2 kbit/sec figure) .

 

Does anyone have any experience with these transceivers handling common async serial data? I am probably most interested in 9600 baud.

 

Many thanks

Jim

 

 

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Jim, I've not worked with one of these, but IIRC the IR signal consists of modulated carrier, but it looks like this xcvr takes care of all that, you just connect it to the TXD/RXD pins and treat it like any other serial comm port.

In low power apps, the SD pin needs to be set to reduce power when not needed. 

Jim

 

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Thanks,

 

I guess the next step is to get a couple and just try them.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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ka7ehk wrote:

Then, in the Receiver characteristics section, it says:

RXD pulse width of output signal, 50 %;  Input pulse width=1.63 μs; 1.7us min; 2us typical; 2.9us max

So, its not clear to me whether the output pulse width varies with the input pulse width. The 1.63us pulse width would appear to correspond to 613 kbit/second (which seems odd, given the max 115.2 kbit/sec figure) .

IINM, that's a reference to the fidelity of the output w.r.t. the received light pulse.  The test conditions are a 1.63 us light pulse input, and the RXD output will exhibit the specified MIN/TYP/MAX values.  In essence, the output pulse will closely match the input light pulse, but will always exhibit some variable amount of pulse stretching.  That 1.63 us light pulse is a standard timing in IrDA 1.3 (I think?).

 

Note that the transceiver is only one layer (layer 1?).  It doesn't provide a protocol stack.  Digikey has an (extremely rudimentary) video survey of IrDA involving a protocol handler device from Microchip, like the MCP2122 series (UART to IrDA):

https://www.youtube.com/watch?v=cN50oM1N1hI

http://ww1.microchip.com/downloads/en/devicedoc/21894c.pdf

 

You could just drive the TFBS4650 via a UART, but that will be suboptimal in the same way that hooking up a simple ASK RF transceiver to a UART would be suboptimal.

 

You can use a protocol handler chip, or implement a software-based protocol handler.  You can use a standard protocol, or devise your own.  Manchester coding is likely to be your friend in that case.

 

Disclosure, I've never worked with IrDA, but coincidentally I have been considering it for a couple of projects, and have done the smallest amount of research so far.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

Last Edited: Mon. Aug 19, 2019 - 07:45 PM
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Thanks for the input. As I suggested above, it looks like it is time to get a couple and just see how they function.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Some of the 3-legged IR Remote Control receivers (TSOP36 or similar) can actually receive uart data (but not all , the datasheet says if they can)

 

I once did a test where i send 1200 BPS via IR-Led to a , using a timer in CTC mode (36KHz) , and a Quad-Nand to gate the 38KHz & Uart data together.

Receiver was a SFH5111 IR Receiver

 

https://www.avrfreaks.net/commen...

 

https://www.avrfreaks.net/commen...

 

IRDA would prob. require an IRDA capable uart.

 

 

PS: Make sure the NAND & driver/receiver inversion levels matches the AVR RX Uart

 

/Bingo

Last Edited: Tue. Aug 20, 2019 - 07:37 PM
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Bingo600 wrote:

Some of the 3-legged IR Remote Control receivers (TSOP36 or similar) can actually receive uart data (but not all , the datasheet says if they can)

Two-way comms would require a receiver and an emitter on each end.  The advantage of something like the TFBS4650 is that it is a transceiver.

 

While config as OP is seeking could be done with one-way comms, two-way allows ack/query.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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I was hoping to have two way. The external device needs to know what current settings are, as well as ACK/NAK.

 

What I found puzzling is that the device (of which Vishay seems to make MANY variants) talks about 9.6 kbits/s to 115.2 kbits/s but THEN says (in Pin Description table)

 

Receiver output. Normally high, goes low for a defined pulse duration with the rising edge of the optical input signal.

Then in the Receiver OptoElectric Characterics, says

 

 RXD pulse width of output signal, 50%; Input pulse 1.63us, 1.7us min, 2.0us typical, 2.9us max

Now, the way I am interpreting it is that the pulse width spec is for the standard IrDA  pulse code signal but that it will accept async serial from 9600 baud to 15200 baud. There are OTHER transceivers that seem to be spec'd for a constant output pulse width (and those seem not to have a bit rate spec). That leads me to think that the latter types have something equivalent to a one-shot in the output buffer. This seems to be consistent with Bingo's post.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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ka7ehk wrote:
talks about 9.6 kbits/s to 115.2 kbits/s
This is a reference to the SIR modulation supported by the device.  That modulation (like some other modulations supported by IrDA) employ an RZI (return to zero, inverted) line coding, whereby a zero is encoded as a pulse equal in length to 3/16th of a bit time, and a one is encoded as no pulse.

 

Bit time for 115,200 baud is 8.68 us, and 3/16th of that is 1.63 us.  That's where the 1.63 us comes from.

 

Have a look at the Wikipedia page for IrDA as a starting point.

 

EDIT:  Also, Vishay have a paper on IrDA physical layer.  Some figures therein may help.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

Last Edited: Wed. Aug 21, 2019 - 04:30 AM
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"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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OK, so maybe those things are not so good for simple async serial. 

 

Thanks

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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ka7ehk wrote:

OK, so maybe those things are not so good for simple async serial. 

Perhaps.  As I said I'm only just now beginning my own research.  I may conclude that a physical connection is more suitable for the close-range comms I'm looking for.  However I don't have your environmental requirements.

 

As mentioned, Microchip have a device which will drive these transceivers, providing a UART interface.  See #36.  The device MCP2122 mentioned provides only drive, not UART, and requires a 16x bit clock be available (and is probably not the best choice for you nor me).  There are other devices which will also provide some level of protocol management.  MCP2150 / MCP2155 assert "Host UART easily interfaces to a modem’s serial port (DCE)".

 

There's also a selection appnote:

http://ww1.microchip.com/downloads/en/AppNotes/91073b.pdf

This may help you determine what problems you need to solve, and whether or not IrDA can help you solve them.

 

Full family:

MCP2120: http://ww1.microchip.com/downloads/en/devicedoc/21618b.pdf

MCP2122: http://ww1.microchip.com/downloads/en/devicedoc/21894c.pdf

MCP2140: http://ww1.microchip.com/downloads/en/DeviceDoc/21790B.pdf

MCP2150: http://ww1.microchip.com/downloads/en/DeviceDoc/21655C.pdf <-- fixed 9600 baud, might be simplest

MCP2155: http://ww1.microchip.com/downloads/en/DeviceDoc/21690B.pdf

 

There are a number of appnotes available as well.  A Google search for part numbers is revealing.

 

While I expect you could implement all of this in software and interface directly to the TFBS4650 or similar, saving the BOM and board space, it might be easier at least at first to play with one or more of these devices.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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So I guess I take it back.  Maybe the MCP2120 would be the best to start with.  The protocol handler chips (40/50/55) are more than what you need, as you don't really need to comply with the higher levels of the IrDA standards.  Do you?  Unless you want this to work with a laptop from the 2000s, or an original Palm Pilot... ;-)

 

 

 

 

The "3 mA typical @ 5.0V when disabled" is a typo I believe.  DC characteristics show 3 uA under those conditions.  They also show a max of 4 uA at 3.0V.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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Bingo600 wrote:
IRDA would prob. require an IRDA capable uart.
megaAVR 0-series and XMEGA

megaAVR 0-series FDS

[page 269]

• IRCOM Module for IrDA® Compliant Pulse Modulation/Demodulation

 

"Dare to be naïve." - Buckminster Fuller

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Thanks, folks!

 

That is an immense help. I was not  looking for information in right place! Review commences shortly.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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From a cursory reading, the 2120 could be handled with as few as 3 pins:  TX, RX, EN(able).  RESET may also be necessary.  CLKIN would also be necessary if not running from its own crystal.

 

Alternately, the 2122 could be handled with 4 pins: 16XCLK, TX, RX, RESET.  The handling will be different, as you need to provide a 16-times baud clock.  This may be the simplest.

 

Yes, I realise I'm wandering in my 'recommendations'.  I'm as new to this as you, and haven't actually put hands on any of these (including the transceiver).  I think if I move forward with this for my own purposes, I'll likely get the transceiver and the 2122, then end up directly driving the transceiver with the AVR after playing with and understanding the function of the 2122.

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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gchapman wrote:

• IRCOM Module for IrDA® Compliant Pulse Modulation/Demodulation

Handy!

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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There's this:

http://www.duris.de/psh/irdavr/irdavr.htm

 

IrDA® lite protocol stack for Atmel AVR microcontrollers

 this Site as pdf-file

Features:

IrDA® lite protocol fully implemented in firmware (only IR-transceiver required)

  • secondary only device
  • fixed speed of 9600 bps, data size =64bytes, window size =1, max. turn arround time 500 ms, disconnect/treshold time of 3 seconds, additional BOFs =0
  • implemented layers: physical, frame wraper, payload and LAP , LMP , TinyTP , IrCOMM and IAS
  • IrCOMM 3 and 9-Wire serial emulation

used

  • one external interrupt input, one general I/O pin as output and one 8-bit timer for timing
  • ca 200 Byte of SRAM
  • ca 3 kByte of Program FLASH

 written in AVR Studio 4.11 (assembler)

IrDA lite for Atmel AVR

 

 

  The IrDA Lite was developed for simple electronic devices with small system resources. For IrDA lite does not exist a defined specification. A Lite implementation can range from a minimum Lite up to a complete IrDA implementation. IrDA Lite is compatible with a fully implemented IrDA stack.

 

You probably could reduce the flash/SRAM footprint by lifting only those layers of the protocol you need, at the expense of not being compatible with standard-compliant devices.  If you're engineering both ends, it won't matter.

 

You could likely also use a pin-change interrupt instead of INT0.  Haven't looked at the code, don't know if it uses level or edge.

 

EDIT:  Hmm... no download link on that page.  Only a contact:

For inquiries and questions please contact irdavr@psh-mikro.sk

It's a 14-yr-old document.  Who knows if anyone will respond.

 

 

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

Last Edited: Wed. Aug 21, 2019 - 03:23 PM
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"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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