@redplc/node-red-rpi-mcp3424
Node-RED node for mcp3424 18bit adc using with redPlc nodes
mcp3424 analog to digital converter
- 12..18bit Conversion Resolution.
- Four Analog Inputs.
- Each input can be disabled.
- Internal Voltage Reference.
- Internal Oscillator.
- Programmable Data Rate 3.75 SPS (18bits) to 240 SPS (12bits).
- The PGA offers input ranges from ±256 mV to ±2048 V.
- I2C Interface with Eight Pin-Selectable Addresses.
- Works also for mcp3421..mcp3428
Usage
- Install redPlc nodes.
- Use redPlc s-inject node for trigger update.
- Connect to first output on s-inject node.
- Daisy chain nodes in series.
- For logical operations use redPlc nodes.
- Data is exchanged with global context variable arrays.
- Array index is equal input number for easy handling.
- This node works on Raspberry Pi with 32bit or 64bit OS.
- Input voltage more than VCC can damage adc input.
- The output value is mV or adc raw data.
- Works also on Raspberry Pi 5
- Enable I2C with raspi-config.
- If other type then mcp3424 used, set correct parameter (see table below).
- If you use i2c-0 port add
dtparam=i2c_vc=on
to /boot/config.txt,
then Pin27=SDA, Pin28=SCK.
- For other ports add this to /boot/config.txt.
Array Index
| Input | Array-Index |
|---|---|
| CH1 | 0 |
| CH2 | 1 |
| CH3 | 2 |
| CH4 | 3 |
Address Pin Connection
| I2C Address | ADR0 Pin | ADR1 Pin |
|---|---|---|
| 68H | Open | Open |
| 68H | GND | GND |
| 69H | GND | Open |
| 6AH | GND | VCC |
| 6BH | VCC | GND |
| 6CH | VCC | Open |
| 6DH | VCC | VCC |
| 6EH | Open | GND |
| 6FH | Open | VCC |
Supported Devices
| Type | # Channel | Max. Resol. | Address-Range |
|---|---|---|---|
| mcp3421 | 1 | 18bit | 68H |
| mcp3422 | 2 | 18bit | 68H |
| mcp3423 | 2 | 18bit | 68H-6FH |
| mcp3424 | 4 | 18bit | 68H-6FH |
| mcp3425 | 1 | 16bit | 68H |
| mcp3426 | 2 | 16bit | 68H |
| mcp3427 | 2 | 16bit | 68H-6FH |
| mcp3428 | 4 | 16bit | 68H-6FH |
Example
This example reads temperature from sensor LM35 (DZ).
The temperature sensor LM35 (DZ) outputs voltage 10.0 mV/°C.
The sensor measures in the range of 2°..150°.
Therefore the output is 20mV..1500mV.
The module node mcp3424 is set for input CH1 and CH2 to Input-Range 2048mV.
Other adc inputs are disabled.
The redPlc calculate node divides adc value to 10.
The redPlc export nodes reads the analog variables and sends to Dashboard gauge.