Eight 24-Bit Analog Inputs DAQ 8-Layer Stackable HAT for Raspberry Pi
Eight Differential or Common Ground 24 bit inputs software selectable to ±0.75V, ±1.5V, ±3V, ±6V, ±12V, ±24V with status LEDs; RS485, Watchdog.
Overview
Eight-layer stackable 24-bit analog input DAQ HAT for Raspberry Pi with 8 differential channels and 8 software-selectable input ranges (±0.18V to ±24V). Supports data rates up to 64 kSPS with internal or external clock and trigger for synchronized multi-card acquisition. Wide-range power supply (5V or 12–24VDC) provides 4A continuous / 5A peak to the Raspberry Pi.
- 8 differential 24-bit analog inputs — software-selectable range ±0.18V to ±24V (8 ranges)
- Data rates up to 64 kSPS; internal or external clock/trigger; synchronized multi-card acquisition
- RS485/MODBUS port; Real-Time Clock with battery backup; hardware watchdog
- Wide-range power supply (5V or 12–24VDC); provides 4A continuous / 5A peak to Raspberry Pi
- Eight-layer stackable — up to 64 differential analog inputs on one Raspberry Pi
- Compatible with all Raspberry Pi versions from Zero to 5
Works with Open Automation Software
Compatible with widely used tools for control, monitoring, and system integration.
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INTERFACES AND I/O
| I/O's | Communication | Software Integration |
|---|---|---|
| • 8 Differential 24-Bit Analog Inputs (±0.18V to ±24V, 8 software-selectable ranges) | • I2C Port to Raspberry Pi | • Command Line |
| • 8 Programmable Threshold LEDs | • RS485/MODBUS Port | • Python Libraries |
| • Push Button (GPIO 26 / pin 37) | ||
| • Real-Time Clock with CR2032 battery backup | ||
| Other Features | ||
| • Software-selectable input range — ±0.18V to ±24V (8 ranges) | ||
| • 64 kSPS max data rate; internal or external clock and trigger | ||
| • Synchronized multi-card acquisition across all stacked cards | ||
| • Hardware watchdog and resettable fuse (4A) | ||
| • Wide-range power supply (5V or 12–24VDC); provides 4A/5A peak to Raspberry Pi | ||
| • TVS protection on all inputs; eight-layer stackable | ||
DESCRIPTION
The Eight 24-Bit Analog Inputs DAQ HAT adds eight differential analog input channels to the Raspberry Pi. Two ADS131 24-bit delta-sigma ADCs deliver up to 64 kSPS with 80 dB dynamic range at maximum rate. All eight input ranges are software-selectable from ±0.18V to ±24V — no hardware changes needed when switching between signal types.
Eight differential channels, with or without common ground. Software-selectable ranges: ±0.18V, ±0.37V, ±0.75V, ±1.5V, ±3V, ±6V, ±12V, ±24V. Input impedance 300 KΩ to 1 MΩ. TVS protection on all inputs.
Two ADS131 24-bit delta-sigma ADCs support data rates up to 64 kSPS with 80 dB dynamic range at maximum rate. Supports internal or external clock and trigger for precise acquisition timing.
The master card sends clock and synchronization signals to all slave cards in the stack, enabling simultaneous sampling across all stacked cards. Ideal for multi-channel data acquisition requiring phase-accurate measurements.
An onboard RTC with CR2032 battery backup keeps accurate time through power failures. Ideal for timestamped data logging in unattended or remote installations where network time is unavailable.
When DIP switches are set to OFF, the card operates as a MODBUS RTU slave — any PLC, SCADA, or HMI can read all input values without a Raspberry Pi. Set to ON for Pi passive bridge mode. MODBUS register map available on GitHub.
The onboard watchdog monitors the Raspberry Pi and power-cycles it if a reset command is not received within the configured timeout. Disabled at power-up; activated automatically after the first reset command. Reset counter stored in flash.
TECHNICAL DETAILS
CARD LAYOUT
MECHANICAL SPECIFICATIONS
DIP SWITCH AND STACKING
The onboard 6-position DIP switch configures the stack address and RS485 port behavior. Up to eight Eight 24-Bit Analog Inputs HATs can be stacked on one Raspberry Pi; cards can be stacked in any order.
| Switch | Name | Function |
|---|---|---|
| TERM | RS485 termination | ON = enables 120 Ω termination resistor; set ON if this card is the last on the RS485 bus |
| TX | RS485 TX select | ON = Raspberry Pi drives RS485 TX; OFF = onboard processor drives TX (MODBUS RTU slave) |
| RX | RS485 RX select | ON = Raspberry Pi receives RS485 RX; OFF = onboard processor receives RX |
| ID0 | Stack ID bit 0 | Binary stack address bit 0 (LSB) — sets card level 0–7 |
| ID1 | Stack ID bit 1 | Binary stack address bit 1 |
| ID2 | Stack ID bit 2 | Binary stack address bit 2 (MSB) |
ELECTRICAL SPECIFICATIONS
| Power | |
|---|---|
| Power supply | 5V/8A or 12–24VDC pluggable connector |
| Provides to Raspberry Pi | 4A continuous / 5A peak |
| Onboard resettable fuse | 4 A |
| Power consumption (card) | 50 mA |
| 24-Bit Differential Inputs | |
|---|---|
| Input ranges (software-selectable) | ±0.18V, ±0.37V, ±0.75V, ±1.5V, ±3V, ±6V, ±12V, ±24V |
| ADC resolution | 24 bits |
| Max data rate | 64 kSPS |
| Input impedance | 300 KΩ to 1 MΩ |
| Input protection | TVS on all inputs |
POWER REQUIREMENTS
Power supply: The card accepts 5V from the Raspberry Pi or its own pluggable connector, or 12–24VDC from a wide-range supply. When a wide-range supply is used, the onboard DC-DC converter provides 4A continuous / 5A peak to power the Raspberry Pi. The card itself draws 50 mA. A resettable 4A fuse protects the board.
COMMUNICATION INTERFACES
HARDWARE WATCHDOG
The onboard hardware watchdog monitors the Raspberry Pi. If the application fails to send a reset command within the configured timeout, the watchdog cuts power to the Pi and restores it after the configured off period. The watchdog is disabled at power-up and is activated automatically after the first reset command is received. Use 24b8vin -h to see all watchdog commands.
| Parameter | Value |
|---|---|
| Initial timeout period | Configurable — allows time for Raspberry Pi to boot and start the application |
| Running timeout period | Configurable — normal operating timeout |
| Off period | Configurable — duration the Raspberry Pi power is cut when timeout triggers |
| Reset counter | Stored in non-volatile flash; can be read or cleared at any time |
COMPATIBILITY
| Interface | I2C |
| GPIO used | GPIO2 (SDA), GPIO3 (SCL) + 1 interrupt pin |
| Max stack | 8 cards of each type — up to 64 differential inputs; different Sequent HATs can be freely mixed |
| Compatible with | All Raspberry Pi versions from Zero to 5 (40-pin GPIO header) |
DOWNLOADS
| Schematics (PDF) | CAD | Software & Integrations |
|---|---|---|
| Schematic V1.1 | 3D STEP Model V1.1 | Command Line |
| 3D Printing Enclosure | Python Libraries |
WHAT'S INCLUDED
When you purchase the card you will receive the following items:
| 1. Eight 24-Bit Analog Inputs DAQ HAT for Raspberry Pi |
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| 2. Mounting Hardware | |
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| 3. Connector Plugs for all Inputs and Outputs | |
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QUICK START
- Plug your card on top of your Raspberry Pi and power up the system.
- Enable I2C communication on Raspberry Pi using
raspi-config. - Install the software from GitHub:
~$ git clone https://github.com/SequentMicrosystems/24b8vin-rpi.git~$ cd 24b8vin-rpi~/24b8vin-rpi$ sudo make install~/24b8vin-rpi$ 24b8vin -h
The program will respond with a list of available commands. To read more about the CLI, please refer to the README file. If you would rather use a different platform, you can access the same functionality through the Python library in the Downloads tab above.
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