Main Site Documentation

FEZ Cobra UART vs ChipWorkx COM3


#1

I completed the prototype application on the ChipWorkx board and after some conversation in that forum decided to implement the solution using FEZ Cobra using the FEZ COBRA PROTOTYPING BOARD. I only use Pins 2, 3, and 5 on the 9 pin. I piped the GND to pin 5 and then COM3RX to pin 2 and COM3TX to pin 3. And that was a guess. When I send the data from the FEZ board to a serial client, the data received is not what I expected. What am I missing?

Thank you,
Rick


#2

I’m thinking I need a rs232 convertor. Does that make sense?


#3

Hi Rick

You should provide more information - 1)Schematic 2) Code Snippet

What are you using on the other end ? If it is a device, is it powered on ? Is the ground connected ?

What baud settings are you using ?

Do your serial lines cross over from TX on Cobra to RX on the other end and RX on Cobra to TX on the other end ?

Are you connecting to a PC ? If yes did you place a RS232 transreceiver like MAX232/3 ?


#4

woah, something screwy deleted my post… anyways, Rajesh covered it.


#5

What are you using on the other end ? If it is a device, is it powered on ? Is the ground connected ?
I am hooking to a PC.

What baud settings are you using ?
9600 8 bits 2 stopbits. Same as the ChipWorkX settings.

Do your serial lines cross over from TX on Cobra to RX on the other end and RX on Cobra to TX on the other end ?
Pins 2 and 3 do cross over on the wire between the PC and the Cobra.

As I read the EMX manual, I think the 232 convertor or the lack there of is the issue.


#6

I would suggest a MAX233. It is 3v and does not need external caps (may be one for decoupling)

…an yes please disconnect and stop hooking up directly to the PC till you fix things … I assume that you are using a USB to serial dongle of sorts … you dont want to fry anything with the RS232 voltage and I hope there has been no damage alrady…