help - z85c30 controller

- S
- sushovande
  
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posted
18 years ago

Tue, Oct 25, 2005 9:07 AM

We are trying to configure a Z85C30 communications controller for communicating with both it's channels simultaneously (We are using Rabbit 3000 as our microprocessor). Channel A is working well as we have a crystal connected across it. Channel B also has a crystal across it, but it is not working

Our results so far: Channel A is working well. Channel B is showing Transmit Buffer Full and Receive Character not Available when we try to do I/O on that port.

Are there any issues with usin both channels on the Zilog Z85C30? Any conflicting settings? We will be very thankful if someone could help. Any further requests for information for configuration is welcome.

Please help.

- A
- Anton Erasmus
  
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posted
18 years ago

Tue, Oct 25, 2005 6:27 PM

What do you mean with "Channel B also has a crystal across it" ? The Z85C30 should have only one crystal for both channels. One can provide an external clock seperately for each channel, but this is normally only used for synchronous protocols. I have been using both channels on the Z85C30 with different processors over many years with no problems.

Regards Anton Erasmus

- M
- Monte Dalrymple
  
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posted
18 years ago

Tue, Oct 25, 2005 7:42 PM

...ahh, someone using two of my designs in the same system...

Seriously though, the two SCC channels are identical. Tx Buffer Full and no Rx Character Available usually implies that there isn't a clock for the receiver and transmitter. Make sure that the oscillator on Channel B is actually oscillating and that you have the clocking options set up properly.

You might also check the bus timing. Make sure that the channel select timing is okay, so that you are actually accessing channel B. But the symptoms say no Tx or Rx clock is present, for some reason.

Monte