Switch Relays from the IO Board

[James Ahlstrom]

I got an email from Bart, PJ2BB, in Curacao requesting help on how to switch relays using the IO board. He has an attached amp, and the bandpass filter relays must be switched by grounding a pin that depends on the band in use. With his permission I am moving the discussion here so that the group can help.

You need low-side switches to switch your relays, and the IO board has seven of them plus an eighth for a DC output. The low-side switches are on J6 pins 1 to 8 and are controlled by the GPIO pins GPIO16_Out1 to GPIO08_Out8. The pins to use are in the protocol document.

You need to connect jumper wires from J6 to the DB9 connector. You should probably connect in pin order, 1 to 1, 2 to 2 etc. Just connect as many pins as you have relays. And be sure to add a ground pin.

These low-side switches are NOT protected against inductive loads. Always place a diode across relay coils and any other inductive load. The diodes should probably go in the amp box and may already be there.

Next you need to create your own main.c, compile it and load it into the Pico. See the protocol document for directions. Start with the main.c in n2adr_basic and delete the code for the antenna tuner and the FT817 band voltage. Change the switch statement to the pattern you need for your relays.

 Please request further help on this group. Good luck!

Jim

N2ADR

[Noel Woodfield]

Jim and Bart

I have done a build that is similar to what Bart is trying to do.

I have the IO board however my solution is not using its functionality. 

I have HL2 and a homebrew LDMOS amplifier. The amplifier LPF board uses the same band steps as the LPF in the HL2.

I connected to each of the HL2 LPF relay feeds on the HL2 LPF board (switched earth for 3V3 relays) and I send this and 3V3 to my amp via the DE9 connector of the IO board.

In the amp I have an interface board that has five optocouplers and five power transistors - this switches the ten 12V relays on the amps LPF board.

No coding but it works.

de Noel ZL2VN

Interface board is top left in photo:

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[Noel Woodfield]