MCO Pin

clanuchnik · ‎2003-06-30

Posted on June 30, 2003 at 13:01

MCO Pin

clanuchnik · ‎2003-06-24

Posted on June 25, 2003 at 06:55

I'm using the ST7LITE09

Internal RC oscillator, PLL x8 Enabled

I'm trying to get the Fcpu in the MCO pin and for this I load MCCSR = $02 If I program the device I don't see any output in the MCO pin, if I run from the application from the inDart the development board crashes and looses communiction with the PC

simonharrison9 · ‎2003-06-24

Posted on June 25, 2003 at 07:09

Hi,

A few ideas:

1. check your IO configuration :

MCO pin needs to be configured as floating input

The ICC communication lines also need to be configured as input

2. Ensure you are communicating to the IC with 'Ignore Option Bytes' setting (Operations -> Communication settings).

3. If you're using LVD, ensure that the mcu supply is above this level.

4. Check the watchdog options settings - use software unless you've written your code with watchdog refresh instructions

regards,

Simon

[ This message was edited by: sjh on 12-11-2003 16:23 ]

p239955_stm1_stmicro_com · ‎2003-06-30

Posted on June 30, 2003 at 12:19

Hi,

In addition to the ideas given, here are some feedbacks:

- I confirm that setting the 'MCO' bit in MCCSR register should be enough to output the CPU clock on the MCO pin

- the MCO pin is shared for ICC communication (ICCCLK signal): you may not be able to output the clock while programming/communicating with your device. In this case, try to program your micro, and run it in the application without ''ICC'' link to the PC.

- Check the reset line to be sure that your device is not under reset, or do not have unwanted reset.

simonharrison9 · ‎2003-06-30

Posted on June 30, 2003 at 13:01

Quote:

On 2003-06-30 15:49, Pedro wrote:

- the MCO pin is shared for ICC communication (ICCCLK signal): ot have unwanted reset.

Hi,

This is a good point that I missed !!!!

You must use the other option in the communication settings - use option bytes, otherwise the inDART will be sending a clock signal to your micro on this pin.

To avoid this conflict, remove the jumpers for the clock selection (J5) on the Softec board if you are using that board, otherwise find some other way to disconnect the pin.

This makes things tricky - you will need to program the device first with an RC clock before doing this - you may need the ICCCLK signal and Ignore option bytes to do this !!!

regards,

Simon