New ST10 project

duncan2 · ‎2003-02-28

Posted on February 28, 2003 at 16:21

New ST10 project

duncan2 · ‎2003-02-27

Posted on February 27, 2003 at 16:38

I have just got an ST10 based system back from the pcb fabricators and I am having trouble getting it going. I have not used ST10 uCs before.

The uC is a 172. I have checke dthe power supplies and reset circuitry and this appears to be functioning correctly. The problem is that the CS0 pin is not moving. The address bus is counting, the RD and ALE pins are bouncing up and down but the CS0 - which is connected to the EPROM CS pin (via an ISP) - is resolutely static.

Any help would be greatly appreciated.

PS. Just how do I get in to the knowledge base? I have registered and an email with a password duly arrived, but the site refuses to accept it! I can only hope this query gets through, after all it's using the same password.

maxime2399 · ‎2003-02-27

Posted on February 27, 2003 at 19:40

I recommend you to check the external bus configuration pull-down resitors on port 0.

During RESET those pin are sampled and the external bus configuration is set-up according to the levels. Those pins have an internal pull-up, so without pull-down resistor, the pin level during reset will be high.

P0H.2 and P0H.1 are controlling the number of chip select line (0 to 5).

I advice you to have a look at the ST10R272 user's manual available

http://www.stmcu.com/mcdfiles/7701.pdf

.

Pages 153-154 and 272-274 should help.

duncan2 · ‎2003-02-28

Posted on February 28, 2003 at 16:21

Thanks.

The device using that port was (unexpectedly) pulling the pins low during reset.