mirror of
https://github.com/maziggy/bambuddy.git
synced 2026-09-30 11:12:35 +02:00
Set up scale readings
This commit is contained in:
maziggy
+49
-8
@@ -27,13 +27,14 @@
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### Setup Steps
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#### 1. Enable SPI
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#### 1. Enable SPI and I2C
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After a fresh Raspberry Pi OS install, SPI is disabled by default.
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After a fresh Raspberry Pi OS install, SPI and I2C are disabled by default.
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```bash
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sudo raspi-config
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# Navigate to: Interface Options -> SPI -> Enable
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# Navigate to: Interface Options -> I2C -> Enable
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sudo reboot
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```
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@@ -42,40 +43,64 @@ Verify after reboot:
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```bash
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ls /dev/spidev0.*
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# Should show: /dev/spidev0.0 /dev/spidev0.1
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ls /dev/i2c-*
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# Should include: /dev/i2c-1
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```
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#### 2. Disable automatic CS (kernel SPI chip-select)
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#### 2. Configure `/boot/firmware/config.txt`
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Since we use manual CS on GPIO23, we need to tell the SPI driver not to
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drive any hardware CS pins. Add this to `/boot/firmware/config.txt`:
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Add the following lines under the `[all]` section:
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```
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# SpoolBuddy: I2C bus 0 for NAU7802 scale (GPIO0/GPIO1)
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dtparam=i2c_vc=on
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# SpoolBuddy: Disable SPI auto CS (manual CS on GPIO23 for PN5180)
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dtoverlay=spi0-0cs
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```
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- `i2c_vc=on` enables I2C bus 0 (GPIO0/GPIO1). The default `i2c_arm` only
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enables bus 1 (GPIO2/GPIO3). The NAU7802 is wired to bus 0.
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- `spi0-0cs` disables the kernel SPI driver's automatic chip-select. We use
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manual CS on GPIO23 because the driver's CS timing doesn't meet the PN5180's
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requirements.
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Then reboot:
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```bash
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sudo reboot
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```
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Verify after reboot:
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```bash
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ls /dev/i2c-0
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# Should exist
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sudo i2cdetect -y 0
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# Should show 0x2A (NAU7802)
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```
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#### 3. Install system packages
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```bash
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sudo apt install python3-spidev python3-libgpiod gpiod libgpiod3
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sudo apt install python3-spidev python3-libgpiod gpiod libgpiod3 i2c-tools
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```
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- `python3-spidev` / `libgpiod3` — system libraries for SPI and GPIO access
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- `gpiod` — command-line GPIO tools (useful for debugging)
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- `i2c-tools` — I2C diagnostic tools (`i2cdetect`, `i2cget`, etc.)
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#### 4. Install Python dependencies (in venv)
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```bash
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pip install spidev gpiod
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pip install spidev gpiod smbus2
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```
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- `spidev` — Python SPI bindings
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- `spidev` — Python SPI bindings (PN5180 NFC reader)
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- `gpiod` — Python GPIO bindings via libgpiod (works on both RPi 4 and RPi 5)
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- `smbus2` — Python I2C bindings (NAU7802 scale)
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#### 5. Solder all connections
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@@ -144,3 +169,19 @@ Place a tag on the reader. Supported tag types:
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| SDA | Pin 27 | GPIO 0 | Yellow |
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| SCL | Pin 28 | GPIO 1 | White |
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| GND | Pin 30 | — | Black |
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> **I2C Bus:** Uses I2C bus 0 (GPIO0/GPIO1), enabled via `dtparam=i2c_vc=on`
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> in config.txt. Bus 1 (GPIO2/GPIO3) is the default but those pins are not
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> used here.
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### Verify
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```bash
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sudo i2cdetect -y 0
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# Should show 0x2A
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sudo python3 spoolbuddy/scale_diag.py
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```
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The diagnostic reads 10 samples at 10 SPS and shows raw ADC values, average,
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and spread. Typical idle readings are around ~500k with a spread under 20k.
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@@ -0,0 +1,170 @@
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#!/usr/bin/env python3
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"""NAU7802 Scale Diagnostic — ported from SpoolBuddy Rust firmware.
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I2C address: 0x2A
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Bus: /dev/i2c-0 (GPIO0/GPIO1 on RPi)
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"""
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import struct
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import sys
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import time
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import smbus2
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I2C_BUS = 0
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NAU7802_ADDR = 0x2A
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# Register addresses
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REG_PU_CTRL = 0x00
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REG_CTRL1 = 0x01
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REG_CTRL2 = 0x02
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REG_ADCO_B2 = 0x12 # ADC output MSB
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REG_ADCO_B1 = 0x13
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REG_ADCO_B0 = 0x14 # ADC output LSB
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REG_ADC = 0x15
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REG_PGA = 0x1B
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REG_PWR_CTRL = 0x1C
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REG_REVISION = 0x1F
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# PU_CTRL bits
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PU_RR = 0x01 # Register reset
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PU_PUD = 0x02 # Power up digital
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PU_PUA = 0x04 # Power up analog
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PU_PUR = 0x08 # Power up ready (read-only)
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PU_CS = 0x10 # Cycle start
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PU_CR = 0x20 # Cycle ready (read-only)
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PU_OSCS = 0x40 # Oscillator select
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PU_AVDDS = 0x80 # AVDD source select
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class NAU7802:
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def __init__(self, bus=I2C_BUS, addr=NAU7802_ADDR):
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self._bus = smbus2.SMBus(bus)
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self._addr = addr
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def close(self):
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self._bus.close()
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def read_reg(self, reg: int) -> int:
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return self._bus.read_byte_data(self._addr, reg)
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def write_reg(self, reg: int, val: int):
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self._bus.write_byte_data(self._addr, reg, val & 0xFF)
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def init(self):
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"""Initialize NAU7802 — matches Rust firmware init sequence."""
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revision = self.read_reg(REG_REVISION)
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print(f" Revision: 0x{revision:02X}")
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# Reset
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self.write_reg(REG_PU_CTRL, PU_RR)
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time.sleep(0.010)
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self.write_reg(REG_PU_CTRL, 0x00)
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# Power up digital + analog
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self.write_reg(REG_PU_CTRL, PU_PUD | PU_PUA)
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# Wait for power-up ready
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for _ in range(100):
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status = self.read_reg(REG_PU_CTRL)
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if status & PU_PUR:
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print(" Power-up ready")
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break
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time.sleep(0.001)
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else:
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raise TimeoutError("NAU7802 power-up timeout")
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# Sample rate: 10 SPS (bits 6:4 of CTRL2 = 0b000)
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ctrl2 = self.read_reg(REG_CTRL2)
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self.write_reg(REG_CTRL2, (ctrl2 & 0x8F) | (0 << 4))
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print(" Sample rate: 10 SPS")
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# Gain: 128x (bits 2:0 of CTRL1 = 0b111)
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ctrl1 = self.read_reg(REG_CTRL1)
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self.write_reg(REG_CTRL1, (ctrl1 & 0xF8) | 7)
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print(" Gain: 128x")
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# LDO: 3.3V (bits 5:3 of CTRL1 = 0b100)
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ctrl1 = self.read_reg(REG_CTRL1)
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self.write_reg(REG_CTRL1, (ctrl1 & 0xC7) | (0b100 << 3))
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# Enable internal LDO (bit 7 of CTRL1)
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ctrl1 = self.read_reg(REG_CTRL1)
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self.write_reg(REG_CTRL1, ctrl1 | 0x80)
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print(" LDO: 3.3V (internal)")
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# Start conversion cycle
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pu_ctrl = self.read_reg(REG_PU_CTRL)
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self.write_reg(REG_PU_CTRL, pu_ctrl | PU_CS)
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print(" Conversion started")
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def data_ready(self) -> bool:
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return bool(self.read_reg(REG_PU_CTRL) & PU_CR)
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def read_raw(self) -> int:
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"""Read 24-bit signed ADC value."""
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b2 = self.read_reg(REG_ADCO_B2)
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b1 = self.read_reg(REG_ADCO_B1)
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b0 = self.read_reg(REG_ADCO_B0)
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raw = (b2 << 16) | (b1 << 8) | b0
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# Sign extend 24-bit to 32-bit
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if raw & 0x800000:
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raw |= 0xFF000000
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raw = struct.unpack("i", struct.pack("I", raw))[0]
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return raw
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def main():
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print("=" * 60)
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print("NAU7802 Scale Diagnostic")
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print("=" * 60)
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scale = NAU7802()
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try:
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print("[1] Initializing...")
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scale.init()
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print("[2] Waiting for first reading...")
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for _ in range(200):
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if scale.data_ready():
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break
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time.sleep(0.010)
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else:
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print(" Timeout waiting for data ready")
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sys.exit(1)
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print("[3] Reading 10 samples (10 SPS = ~1 second)...")
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readings = []
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for i in range(10):
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# Wait for data ready
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for _ in range(200):
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if scale.data_ready():
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break
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time.sleep(0.010)
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raw = scale.read_raw()
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readings.append(raw)
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print(f" Sample {i + 1:2d}: {raw:>10d}")
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avg = sum(readings) / len(readings)
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spread = max(readings) - min(readings)
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print(f"\n Average: {avg:>10.0f}")
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print(f" Min: {min(readings):>10d}")
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print(f" Max: {max(readings):>10d}")
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print(f" Spread: {spread:>10d}")
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print("\n" + "=" * 60)
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print("Diagnostic complete!")
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print("=" * 60)
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except Exception as e:
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print(f"\nERROR: {e}")
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import traceback
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traceback.print_exc()
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sys.exit(1)
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finally:
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scale.close()
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if __name__ == "__main__":
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main()
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