132 lines
3.1 KiB
Markdown
132 lines
3.1 KiB
Markdown
# Board Pinout & Pinmux Reference
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## LicheeRV Nano (SG2002)
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### I2C Buses
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| Bus | Pins | Notes |
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|-----|------|-------|
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| I2C-1 | P18 (SCL), P21 (SDA) | **Shared with WiFi SDIO** — must stop WiFi first |
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| I2C-3 | Available on header | Check device tree for pin assignment |
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| I2C-5 | Software (BitBang) | Slower but no pin conflicts |
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### SPI Buses
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| Bus | Pins | Notes |
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|-----|------|-------|
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| SPI-2 | P18 (CS), P21 (MISO), P22 (MOSI), P23 (SCK) | **Shared with WiFi** — must stop WiFi first |
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| SPI-4 | Software (BitBang) | Slower but no pin conflicts |
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### Setup Steps for I2C-1
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```bash
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# 1. Stop WiFi (shares pins with I2C-1)
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/etc/init.d/S30wifi stop
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# 2. Configure pinmux for I2C-1
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devmem 0x030010D0 b 0x2 # P18 → I2C1_SCL
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devmem 0x030010DC b 0x2 # P21 → I2C1_SDA
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# 3. Load i2c-dev module
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modprobe i2c-dev
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# 4. Verify
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ls /dev/i2c-*
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```
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### Setup Steps for SPI-2
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```bash
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# 1. Stop WiFi (shares pins with SPI-2)
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/etc/init.d/S30wifi stop
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# 2. Configure pinmux for SPI-2
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devmem 0x030010D0 b 0x1 # P18 → SPI2_CS
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devmem 0x030010DC b 0x1 # P21 → SPI2_MISO
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devmem 0x030010E0 b 0x1 # P22 → SPI2_MOSI
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devmem 0x030010E4 b 0x1 # P23 → SPI2_SCK
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# 3. Verify
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ls /dev/spidev*
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```
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### Max Tested SPI Speed
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- SPI-2 hardware: tested up to **93 MHz**
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- `spidev_test` is pre-installed on the official image for loopback testing
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---
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## MaixCAM
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### I2C Buses
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| Bus | Pins | Notes |
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|-----|------|-------|
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| I2C-1 | Overlaps with WiFi | Not recommended |
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| I2C-3 | Overlaps with WiFi | Not recommended |
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| I2C-5 | A15 (SCL), A27 (SDA) | **Recommended** — software I2C, no conflicts |
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### Setup Steps for I2C-5
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```bash
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# Configure pins using pinmap utility
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# (MaixCAM uses a pinmap tool instead of devmem)
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# Refer to: https://wiki.sipeed.com/hardware/en/maixcam/gpio.html
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# Load i2c-dev
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modprobe i2c-dev
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# Verify
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ls /dev/i2c-*
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```
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---
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## MaixCAM2
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### I2C Buses
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| Bus | Pins | Notes |
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|-----|------|-------|
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| I2C-6 | A1 (SCL), A0 (SDA) | Available on header |
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| I2C-7 | Available | Check device tree |
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### Setup Steps
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```bash
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# Configure pinmap for I2C-6
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# A1 → I2C6_SCL, A0 → I2C6_SDA
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# Refer to MaixCAM2 documentation for pinmap commands
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modprobe i2c-dev
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ls /dev/i2c-*
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```
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---
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## NanoKVM
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Uses the same SG2002 SoC as LicheeRV Nano. GPIO and I2C access follows the same pinmux procedure. Refer to the LicheeRV Nano section above.
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Check NanoKVM-specific pin headers for available I2C/SPI lines:
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- https://wiki.sipeed.com/hardware/en/kvm/NanoKVM/introduction.html
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---
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## Common Issues
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### devmem not found
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The `devmem` utility may not be in the default image. Options:
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- Use `busybox devmem` if busybox is installed
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- Download devmem from the Sipeed package repository
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- Cross-compile from source (single C file)
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### Dynamic bus numbering
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I2C adapter numbers can change between boots depending on driver load order. Always use `i2c detect` to find current bus assignments rather than hardcoding bus numbers.
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### Permissions
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`/dev/i2c-*` and `/dev/spidev*` typically require root access. Options:
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- Run picoclaw as root
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- Add user to `i2c` and `spi` groups
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- Create udev rules: `SUBSYSTEM=="i2c-dev", MODE="0666"`
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