Pi Pico - not "talking to" SC114

[Daniel Coles]

Hi,

I have the SC114 Z80 which seems to work OK when connected to COM port and PuTTY.

I've made the Pi Pico VGA kit, but it doesn't seem to "talk" to the Z80.

The keyboard works as I am able to load up the help menu, but pressing the reset button on the Z80 doesn't cause anything to happen. The jumpers are both set to 1, but no luck in getting it to connect. Is there something obvious I could be missing, or will it be a case of going round with a multimeter again and see if I'm missed any solder connections?

Thank you

[Steve Cousins]

Hi Daniel

Are you using SC114's built in 9600 baud serial port?

If so, the problem could be due to the serial TX and RX signals from the built in port not being connected to the bus pins 35 and 36. They are not connected to the bus as it is expected most people will add a faster serial module which would then cause a conflict.

Steve

[Daniel Coles]

Hi Steve,

Thank you for the reply.

I've tried with the built in port as well as with the SC139 connected.

On the SC139 the jumpers are set as follows (these could well be wrong!)

JPA has a jumper on the leftmost pin, JP5 has a jumper, and JP4 has a jumper.

No jumpers on JP1, 2 or 3.

Thank you,

Dan

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[Steve Cousins]

You need a jumper on JP1 and on JP2 on SC139 to connect TX and RX to the bus pins 35 and 36. The Pi Pico VGA has its RX and TX signals connected to these bus pins, thus allowing communications between it and SC139.

Steve

[Daniel Coles]

Thank you!!!!

I had tried that and there was no change, other than the cursor moving one place to the right.

Connected the USB serial to the main board, rather than to the SC139 and it works!

Thank you for your help, I can actually start to play with it now I'm less disheartened by it!

To view this discussion, visit https://groups.google.com/d/msgid/rc2014-z80/c9e47793-8600-4904-9df0-22cd9f0bd4dfn%40googlegroups.com.