New entry for USB connectivity from Maxim?

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I just got a Maxim flyer touting the MAX3420E "Add USB to Any System with a Single IC". There seem to be very few external components needed, DigiKey has some in stock, and pricing seems to be lower than FTDI models. The uC interface is SPI.

At first blush it looks like a good competitor to FTDI & Silabs offerings. Has anyone worked with them?

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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There was an article about this in the July 2005 Circuit Cellar that got me so excited that I soiled my Depends. But I couldn't get the part for love, money, or terrorist threats. I even contacted the author.

My guess is that they jumped the gun and had to hold off until they got it right.

Anyway, I'm off to get one, as soon as I get a new case of adult diapers.

[edit] So DigiKey has 0 in stock. Well, at least I'll save on paper products[/edit]

Smiley

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Sorry, Smiles, I knew that I checked stock and DigiKey >>listed<< one flavour, but...

Anyway, Maxim has one flavour in stock:

Quote:

MAX3420EECJ+ TQFP Extended (-40 deg C to +85 deg C) 1 Price $ 4.08 $ 3.79 $ 3.58 $ 3.05 $ 2.65
Leadtime In Stock In Stock In Stock In Stock In Stock

[edit] Maxim pretty much does no-questions-asked free sampling, so you might want to just "ask" for a couple.

Lee (just running up my post total by sending Smiley on a wild USB chase)

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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No drivers, and likely to have Maxim's traditionally poor availability.
If you need more speed than the FTDI can do you're probably better off using an MCU with onboard USB anyway. If not, the cost & hassle of driver development would outweigh any benefit in parts cost. Can't see many people wanting to use it...

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[full disclosure: I've only worked with FTDI COMx USB with my AVRs.]

In this modern age, isn't the cute thing to be one of the "classes" that Windows supports? And can't that be done fairly easily with the Maxim offering? E.g.,

Quote:
How many endpoints does the MAX3420E support?
The MAX3420E contains four endpoints:
EP0, bidirectional CONTROL endpoint, 64 byte FIFO.
EP1, OUT BULK or INT endpoint, 2x64 byte double-buffered FIFOS
EP2, IN BULK or INT endpoint, 2x64 byte double-buffered FIFOS
EP3, IN BULK or INT endpoint, 64 byte FIFO
With these endpoints, it is possible to build USB peripherals that support popular USB class drivers, such as a Human Interface Device (HID), Mass Storage, Picture Transfer Protocol (PTP), and Printer.

So you pretend to be one of the supported classes. Hmm--I don't see comm port in there anywhere--I thought that was built-in to XP?

Quote:

How does my Windows application talk to the MAX3420E?
A Windows application talks to the PC's USB host controller through a driver. The driver may be built into Windows or it may be custom. Windows includes built-in drivers for standard device classes, such as Human Interface Devices (HID) and Mass Storage Devices. If your firmware supports one of these standard classes, your customer does not need to load a custom driver.
If you are designing a device that does not conform to one of the built-in Windows standard device classes, the end user must install a custom driver when your USB device is plugged in the first time.

Does Maxim supply a custom Windows driver?
No.
What example code does Maxim supply?
You can find example C code for implementing a HID application on the Maxim website at USB Enumeration Code (and More) for the MAX3420E. This example code emulates a PC keyboard, which types a text string into any Windows application that accepts text (e.g., Notepad) whenever a pushbutton is pressed. By conforming to the standard HID class, the application runs without a custom Windows driver. Regardless of your target application, most of this example code is USB 'boilerplate' that can be used as a starting point for your code.
I want to design a MAX3420E-based device that does not conform to a standard Windows class. What do I use for a Windows driver?
There are two alternatives:
Write the Windows driver yourself. This is complex and difficult, recommended for specialists only.
Purchase a general-purpose driver. These typically consist of the USB driver and a companion library of C functions to access the driver. Drivers are matched to the VID (Vendor ID) and PID (Product ID) in your device descriptor.
Microsoft has announced a general-purpose BULK driver for USB in the upcoming "Vista" version of Windows.
How does the MAX3420E compare with USB 'serial bridge' chips?
USB serial bridge chips connect to a PC using its USB port, but appear as a virtual COM port to the application running on the PC . A custom driver, supplied by the chip vendor, is required to do this COM-USB transformation. A Windows application that talks to a serial (COM) port (e.g., HyperTerminal) can be used to talk to an USB-connected device using this method.
The advantage of this approach is that no enumeration firmware or host driver is required. The disadvantages are in performance, flexibility, and support:

Performance: Because the bridge approach emulates a serial port, the maximum achievable bandwidth is about 1 Megabit per second, well below the USB signaling rate of 12 Megabits per second.
Flexibility: The serial-USB bridge chips are hard-wired to emulate serial-port devices. They are not capable of implementing standard Windows class devices (like HID) or custom device types.
Support: A product you design using one of these chips will require the companion driver to be installed by your customer. Because it is a custom driver, it is not guaranteed to work with future versions of the operating system. If you choose this approach, try to make sure that the vendor is committed to supporting the driver for the lifetime of your product.
What are the advantages and disadvantages of the MAX3420E approach?
The disadvantages are that firmware is required for the MAX3420E controller and that Maxim does not supply a custom Windows driver. Instead, Maxim supplies example firmware to illustrate how to conform to a standard Windows device class (HID), and thereby to use a built-in Windows driver.
The advantages to the MAX3420E approach are performance, flexibility and support.

Performance: The MAX3420E SPI port (its interface to the controller) can run up to 26MHz. If the controller supports a high SPI clock rate, the MAX3420E can support USB transfers up to the maximum available full-speed bandwidth of 12Mbps.
Flexibility: The personality of a device using the MAX3420E is entirely determined by its firmware. Therefore, it can implement any type of USB device.
Support: Once operating systems natively support general USB (BULK) transfers, the need for serial-USB bridge chips will rapidly diminish.

(above from http://www.maxim-ic.com/appnotes... )

I hear you on the Maxim phantoms--big fanfare, samples in hand and tested, production quantities never show up at the distributors.

It certainly looks like they put quite a bit of effort into the supporting documnetation, such as the completely-worked HID "panic button" example.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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I've been burned by Maxim so many times as of 6-7 years ago I haven't used them. Don't make the mistake of relying on their lead times. Actually, I don't miss them and I've done a couple hundred hardware designs since. I was really bummed when thay bought Dallas. Don't use them now either. Too many manufactures actually make the parts they advertise to bother with Maxim.

K

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Second all of the above.

Last few projects I've found it cheaper to spec a USB->serial converter cable; these are super inexpensive in mid volume, and you need the cable anyway.

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seems that Atmel has just come out with some USB AVRs...
http://www.atmel.com/dyn/products/product_card.asp?part_id=3875

with appnotes for making a USB mouse / keyboard.

Though, I wouldn't hold my breath on availability.

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Now that is a step in right direction (AVR with USB). I only wish there was an USB flavour of every device in ATmega range, not just the 128..

The Dark Boxes are coming.

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I'd settle for a USB equivilant of the MAX3100 IC (SPI UART). If it's available, and perferably second, and maybe third sourced. I've still got the heebie jeebies about specing single source USB IC's.

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theusch wrote:

So you pretend to be one of the supported classes. Hmm--I don't see comm port in there anywhere--I thought that was built-in to XP?

Lee

Hi Lee,
I don't think it's so much pretending, it's more like just how its done. Cypress are pretty much the same. When you connect a USB device to the computer, a request is made from the Host (Computer) to ask "who and what are you". I think I have the order right here, the first thing Windows does is check your products Vendor ID (each company manufacturing a USB device needs their own) and product number (each product must be different) to their driver list.

If a driver from your product doesn't exsist they take the descriptor table exchanged, which defines your product as a mouse for example and match it to one of their own. If they can't even do that, you get the new device message and your asked to install a driver.

FTDI do include a driver (unless I'm mistaken) to acheive their magical effect of appearing as a virtual com port.

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The reason I said "pretend" is that I might "pretend" to be a mass-storage device for ease of interfacing, but my "mass storage" could be several channels of temperature A/D readings or such.

So if the Maxim chip turns out to be not a phantom, and is attactively priced, and requires few external components, and can fairly easily pretend :) to be one of the standard classes, then the lack of a provided Windows driver isn't a killer factor and may make an interesting design decision on my next USB project.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Both FTDI and SiLabs provide virtual com port drivers.

I personally find virtual comp ports much easier to use than the standard class drivers, but I have to admit that I haven't tried all that hard to use them. I already had a bunch of code for the com ports so unless I get the notion that I can save enough money using parts that don't provide virtual com port drivers, I think I'll stick with the SiLabs parts.

So far, every time I get all excited about a new USB part, after I do the analysis, I go back to SiLabs.

Smiley

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Hey,

And FTDI has support in Linux built into the Kernel for any recent build. For me that's enough of a reason to choose the FTDI over any device ;-)

Regards,

-Colin

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For me, the SPI interface of the Maxim chip is attractive. Most of my applications already use the USART and SPI. Simply adding another chip select is about as light (hardware-wise) that one could ask.

Like most of you, I am NOT holding my breath on this one. But, if it does happen and is available from DigiKey, hey, who knows! Maxim does make some very attractive chips and when they do get to market with someing genuinely innovative, they are often a year or more ahead of the competition. But my big project that will use a high-side current sense (and some other things) has drug on for so long that now, there are non-Maxim alternatives. Thats what happens!

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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I have 2 samples in my hand.....Got to make an adapter board and try these out!! Though, I like the new USB AVRs better...no extra ICs and almost the same price as the Maxim,SILabs,and Maxim USB chips.(10K pricing) I think Atmel learned from the Butterfly sales......$30 USB AVR evaluation board, no programmer needed!


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