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usb startup issue w/ CFA634-TMC-KU

iveygman

New member
I got one of these not long ago for a work project. It works just fine when I run it on my Windows XP virtual machine (I run Win7 and don't want to install the drivers on that OS for various reasons).

My project is based around a Maxim MAXQ2000 microcontroller module which contains an FTDI FT232BL chip to facilitate USB-to-serial communications. With the drivers I have for that, I am able to talk to a Realterm session within Win7 with no issues from my microcontroller's USB port (it's on COM9 if that matters at all). The problem is that when I actually connect the serial display to the module through its USB port, it won't even power on.

I am told that this is because the local OS needs to send some signal to the USB daughterboard to tell it that it should power on and prepare to receive data, however I was not told what this signal is. I can't exactly just download and install driver software from the website on my 16-bit micro which is programmed in Assembly, so please let me know what I should do.

One thought is that I need to clear the DTR pin somehow to enable the module to receive data, since I sometimes have to do this manually via Realterm, but I'm not sure what I need to do here.

Please advise.
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CF Tech

Administrator
The USB of the CFA634-TMC-KU is a USB device.

The USB on the project board ( FTDI FT232BL ) is also a USB device.

These cannot talk to each other without a USB host.

You would want to use the USB on the Maxim to talk "upstream" to a Windows or Linux USB host.

You would want to use a different serial port on the Maxim to talk to a serial display.

Our tech support guys can convert the CFA634-TMC-KU (USB) into a serial for you.
 

iveygman

New member
I see. Would I require additional circuitry to level-shift between a 3.3V serial output and standard RS-232? My module lacks anything other than the 3.3V level lines.
 

CF Tech

Administrator
If you could use a CFA-533, it can run at 3.3v--and with its logic level option you would not need a translator.

For the other serial modules you would need to translate to full-swing RS-232 or 0-5v logic level inverted RS-232.
 
USB LCD Displays - Graphic and Character LCDs with a Keypad

iveygman

New member
Thanks!

I've actually got some space to implement a pretty simple level shifter, so I'll try it with an old CFA632-YFB-KS I have lying around.
 
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