Firecracker Serial Board Interfacing Question

bxdobs
Posts: 3
Joined: Thu Dec 19, 2019 3:17 am

Firecracker Serial Board Interfacing Question

Postby bxdobs » Sat Jan 03, 2026 12:19 am

Back in another lifetime, X10 designed a RF interface to their powerline controllers ... the Firecracker had 2 versions one uses a comport the other a usb ... I have a Serial Port version that still works ... wrote a C code version to work with HA (home assistant) ... but thinking this could be more useful controlled by an esp32 instead of wasting resource on a PC ... at issue is this device DOESN'T actually use traditional TX/RX serial commands ... instead ... it pulses the RTS and DTR lines to effectively send an RF signal. As a PC RS232 basically doesn't use the Negative going part of a RS232 control or TX/RX, RTS and DTR could potentially be simulated with a 0 to 5V transitions ... MY QUESTION ... how does ESP32 control the CTRL lines on any of its 3 uarts? Should I just ignore these UART Features and just select 2 available GPIO's to drive 2N3906 transistors to the 5V rail? Thanks for any insight you can provide

MicroController
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Joined: Mon Oct 17, 2022 7:38 pm
Location: Europe, Germany

Re: Firecracker Serial Board Interfacing Question

Postby MicroController » Sun Jan 04, 2026 10:20 am

Should I just ignore these UART Features...
Yes, you likely cannot use the UART to generate the required protocol at all.
Manual GPIO may be ok. If you need more speed/timing accuracy you can look into the RMT or SPI.

I think you should also be able to output one signal to two pins while having the hardware invert one of them.

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