topic Re: UART Communication in ColdFire/68K Microcontrollers and Processors

UART Communication

blakehodder — Fri, 08 Feb 2013 12:38:33 GMT

Hi,

I am using a MCF52255 and trying to use the UART without using the RTOS. Could someone please point me in the direction of an app note or other documentation on this.

Regards,

Blake

Re: UART Communication

DavidS — Wed, 27 Feb 2013 20:15:14 GMT

Hi Blake,

You can goto the MCF5225x product page on the Freescale website (or google it) and select the Software/Tools tab.

It has baremetal example code:

MCF5225X_SAMPLE_CODE: MCF5225x_SAMPLE_CODE.

Size (K): 1427 Format: zip Rev #: 0 Modified: 12/22/2008

Please note that as product age, so do the examples implying that the latest IDE's like CW10.x might not be supported.

Regards,

David

Re: UART Communication

blakehodder — Wed, 27 Feb 2013 20:30:06 GMT

Hi David,

I now have my uart working at the right baud but when I am sending something such as 0x4A its sends ok but will change to 0x29.

What would cause this?

Blake

Re: UART Communication

DavidS — Wed, 27 Feb 2013 21:38:50 GMT

Hi Blake,

Are you setup a simple MCF52259 to a PC terminal window?

Have you oscoped the output?

Regards,

David

Re: UART Communication

blakehodder — Thu, 28 Feb 2013 13:04:20 GMT

Hi David,

Actually at the moment I am connected to a PC via a logic analyzer. If I send 0x55 it works no problem and always sends 0x55 but when I send 0x4A or other values thats when it changes. This is how I send it:

void putc(char val)

{

while(!(MCF_UART0_USR & MCF_UART_USR_TXRDY) || !(MCF_UART0_USR & MCF_UART_USR_TXEMP) ){

}

MCF_UART0_UTB = val;

}

Blake

Re: UART Communication

blakehodder — Thu, 28 Feb 2013 16:11:37 GMT

Hi David,

I was over pushing my uart. The MCU was running at such a rate that since I was only sending a value with my program that the uart was not keeping up with the MCU. Once I stuck the delay in, it functioned perfect.

Thanks for all your help.

Blake