What's the best (largely defined as "cheapest") hardware to add to an AVR design to allow comms with a typical PC, one that has USB but no RS-232 ports? I have seen the FT232R family of chips used, is that the device of choice? Are there similar devices hiding under different part numbers?
Also, any other tips, tricks and/or warnings on this subject are welcome. Thanks.
Mike
glitch 
Future Technology: FT232 http://www.ftdichip.com/FTProduc...
Silicon Labs: 210x https://www.silabs.com/products/...
Prolific: PL2303 http://www.prolific.com.tw/eng/P...
The above 3 are probably the most common, and can be found in 90% of the USB-RS232 cables out there.
If you're looking for cheap, consider buying an off the shelf cable, and then using normal RS-232 converters on your boards. Unless you absolutely need your board to have USB on it.
Another USB solution would be to use one of the USB AVR's, an implement whatever device class you want.
clawson 
The crystal is not necessary with ATTiny85's clocked with the internal 16.5 MHz PLL calibrated against USB timing, at least for hobby use. Here's a 12 cell lithium ion battery management system on a breadboard; the IR to USB bridge is the left chip. Below is the text input to a laptop, it's rock solid.
rjburke377 
That's a 45V, I've tried one of those and it didn't work. What is your success rate?
rjburke377 That's a 45V, I've tried one of those and it didn't work. What is your success rate?
/RJ
clawson
No crystal and no connector needed. Using V-USB protocol stack on Tiny45 /w USB HID descriptor. No application driver is needed for Windows.
Now you've got me confused. I could have sworn you started a thread the other day where 30% of your V-USB design wasn't working and the conclusion of it was that a crystal made 100% work OK. Did I just dream that?
Cliff
rjburke377 Now you've got me confused. I could have sworn you started a thread the other day where 30% of your V-USB design wasn't working and the conclusion of it was that a crystal made 100% work OK. Did I just dream that?Cliff
You can read updates here: https://www.avrfreaks.net/index.p...
Summary: 100% success. 64 byte transfers work fine. Next test is 128 byte transfers.
/RJ
sirurx You can also use FT245 in parallel mode, if you don't like serial way;)
You can get best and cheapest if you use both, together it's impossible.
rjburke377 You can also use FT245 in parallel mode, if you don't like serial way;)
You can get best and cheapest if you use both, together it's impossible.
/RJ
sirurx sirurx wrote:So FT245 is the best solution? Why?You can also use FT245 in parallel mode, if you don't like serial way;)
You can get best and cheapest if you use both, together it's impossible./RJ
rjburke377 I use in simple projects FT232 but FT245 has faster transfer and R/W signals so nothing gets lost. Also in parallel mode you don't care about AVR clock frequency as there is no serial channel between usb and AVR and therefore timing is not an issue.
/RJ
maximax Cheapest I can get FT245 in the UK is 2.90GBP ~ 3.00EUR
If you only need a USB 1.1 compliant low-speed device then V-USB is by far cheaper.
Works for me though I am just a hobbyist. If I was thinking of a commercial product I'd probably opt for one of the usb2 compliant FTDI chips. Or even a USB enabled AVR. :wink:
rjburke377 Cheapest I can get FT245 in the UK is 2.90GBP ~ 3.00EURIf you only need a USB 1.1 compliant low-speed device then V-USB is by far cheaper.
Works for me though I am just a hobbyist. If I was thinking of a commercial product I'd probably opt for one of the usb2 compliant FTDI chips. Or even a USB enabled AVR. :wink:
Even a commercial solution may be price sensitive. A 3.00EUR part will add additional sunk and per unit costs and may cause a business case to fail. To use a familiar phrase "The best solution depends on the requirements."
/RJ
wek If you only need a USB 1.1 compliant low-speed device then V-USB is by far cheaper.
Works for me though I am just a hobbyist. If I was thinking of a commercial product I'd probably opt for one of the usb2 compliant FTDI chips. Or even a USB enabled AVR. :wink:
JW
rjburke377 Note that "software USB stack" also eats up a certain amount of resources in the AVR, and imposes limitations on interrupt latencies.
This is incorrect and except for laymen, unacceptable.
JW
/RJ
wek "this" is exchanging "USB2.0" freely for "High Speed".
It appears to be hard to explain even to those otherwise knowledgeable, so explaining it to laymen is usually waste of time (they listen - partially - only when they buy some "USB2.0" labelled equipment and get angry at how slow it is).
JW
rjburke377 "this" is exchanging "USB2.0" freely for "High Speed".It appears to be hard to explain even to those otherwise knowledgeable, so explaining it to laymen is usually waste of time (they listen - partially - only when they buy some "USB2.0" labelled equipment and get angry at how slow it is).
JW
/RJ
"this" is exchanging "USB2.0" freely for "High Speed".It appears to be hard to explain even to those otherwise knowledgeable, so explaining it to laymen is usually waste of time (they listen - partially - only when they buy some "USB2.0" labelled equipment and get angry at how slow it is).
JW
Funny that you bring that up.
I was at the USB committee meeting where Intel, Microsoft, HP, and Compaq joined forces and killed one of my proposals to be able to distinguish between different USB 2.0 implementations.
It was so that consumers would be able to tell the difference between a "real" 2.0 device and one that was merely compatible with the USB 2.0 bus.
(It's an even bigger deal for Hubs than in Devices)
Intel and Microsoft bashed the proposal saying they didn't want to confuse people. They wanted to keep it simple and that there should only be "1" USB.
I wanted a new logo to indicate true high speed support.
(Actually its more complex than just a speed issue but in the name of simplicity I was willing to reduce the new logo down to some sort of "high speed" designation)
Intel and Microsoft were able to get the majority of voting members to vote their way. It sucked, I lost, and I think it has confused the market ever since.
At the time it literally bankrupted some small companies that had built high performance USB 2.0 products because their products cost more than the simpler slower devices and the consumer had no way of knowing the difference between them.
I tried.....
--- bill
