2026-01-28 23:19:46Peter van Dijk:
add more notes (on mpcie pin count)
miners/nebra outdoor.md ..
@@ 187,3 187,41 @@
|__ Port 007: Dev 007, If 0, Class=Human Interface Device, Driver=usbhid, 480M
|__ Port 002: Dev 004, If 0, Class=Vendor Specific Class, Driver=cp210x, 12M
```
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# nebra miner minipcie pin count
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[Nebra](https://github.com/NebraLtd/nebra-lora-hardware/blob/master/Smart-Outdoor-Mainboard-V1/HARDWARE/Pi%20Supply%20Smart%20LoRa%20Gateway%20Schematic.pdf) gives us, per minipcie slot, SCLK+MISO+MOSI+CE+RST. [lora-pipe config.h](https://github.com/folkertvanheusden/lora-pipe/blob/master/config.h) suggests we want SCLK+MISO+MOSI (+CE but maybe we can get away without it)+DIO1(interrupt)+RST. We also need BUSY, for a total of 7 pins. If we hardware CE to always be on, we free up one pin, giving us exactly enough to put DIO0+RST on? Turns out this is "not legal". One more pin if we can abuse GPS_PPS but I don't think we can (or if we can, it would still be shared between the two lora minipcie slots).
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From `hpux735` on the meshcore discord: how about an i2c port expander? 5 pins fits SCLK/MISO/MOSI and all of I2C. You'd have to poll the IRQ. (Or maybe if I'm polling anyway, who needs the IRQ).
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From `Mike's Allotment` on the meshcore discord: UART module instead of SPI?
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Full pin list:
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* SCLK
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* MISO
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* MOSI
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* CE
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* IRQ
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* BUSY
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* RST
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Wired pins on Nebra:
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* SCLK
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* MISO
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* MOSI
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* CE
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* RST
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What if CE, when disasserted, makes BUSY readable on the RST pin, and when asserted, makes RST writable on the RST pin? I wonder what RST with CE asserted means.
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MISO is inactive when CE is off, and CE is always off if BUSY is on.
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What if KISS (TNC) over SPI, or UART bitbang, with a simple MCU.
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What if SPI but something is interposing/reading along to pick up a special frame that means RESET. Then we can reuse the RST pin for BUSY. IRQ was always optional.
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https://github.com/thekakester/Arduino-LoRa-Sx1262/blob/main/src/LoraSx1262.cpp#L230 -suggests- that BUSY can be inferred from GetStatus. This seems to be right for "Transmission is done" but I'm unsure it works for all busy reasons.
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https://www.haraldkreuzer.net/en/news/LoRa-with-the-ESP32-and-Semtech-SX1262 is a very good page that tells us that TxDone and RxDone can be polled instead of IRQed.
