Electrical – Parallel programming with SWD pinouts

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I need to program 8 boards with SWD interface device but I have one programmer with 4 channels.

Is it sufficient if I connect SWD lines in parallel permanently to all 8 boards and just toggle the power in groups? First four powered on, then program. Switch off first '4 group' and power on the 2nd '4 group(5-8)' and program 2nd group?

Do I need to keep the RESET low for 2nd group when 1st is being programmed or power on/off is enough?

Best Answer

Is it sufficient if I connect SWD lines in parallel permanently to all 8 boards and just toggle the power in groups?

No. The unpowered chips will either not allow the SWD lines to go high or pull power of them if the driver is "strong" enough. Rememer that those I/O pins usually have diodes to both VCC and GND rails included.