Hi,
I'm trying to get an eZ8 microcontroller running with the minimal configuration necessary to communicate with the on-chip debugger. Currently I'm using a Parallax Propeller QuickStart board in my attempt, mainly because the operating voltages of the Propeller and the eZ8 match. I have not had any luck so far. I'm doing this purely out of curiosity and an interest in learning how these things work. It seems like a fairly basic task
Initially, I was trying to use a square wave output generated by the Propeller as a clock input to the eZ8, but have since connected an 18.432MHz crystal as shown on page 217 of the eZ8 manual. I have full-duplex serial communication set up on the Propeller, which I have connected to the eZ8's DBG pin, as shown on page 204 of the eZ8 manual. I have kept the baud rate relatively low, in the 75-150 range. I have also connected the eZ8's reset pin to a pin of the Propeller so that I can reset it as needed, and I've connected all of the VDD and VSS pins of the eZ8 (6 total) to the appropriate connections; all of this is on a solderless breadboard. All of the other pins have been left unconnected.
I am trying to send the 0x80 required to initialize the AutoBaud detector (p. 206, eZ8 manual), followed by various read commands (p. 209, eZ8 manual), checking for a response after each. I am getting no responses. I believe that the serial library is working on the Propeller side because when I turn off the library's FDSERIAL_MODE_IGNORE_TX_ECHO flag, I can see the commands that I've sent via the transmit pin being returned via the receive pin.
So, my questions:
Did I miss something? Is more than clock/reset/VSS/VDD required to get the eZ8 running?
It would be helpful if I could separate the minimal configuration problem from the serial communication problem. Is there a way to tell that the eZ8 is in fact running that is less complicated than attempting to communicate with the on-chip debugger?
Any additional thoughts are welcome..
Here's the eZ8 manual: http://www.zilog.com/docs/z8encore/PS0199.pdf