NI Evaluation Board V1

The NI Evaluation Board V1 is an industrial-grade I/O board built on the ESP32. It exposes digital inputs, relay outputs, 0-10V analog outputs, pulse counters, RS485/Modbus, a push button, and PWM — all through a single Arduino library, and it works with the Hyperwisor firmware SDK.

Features

8 digital inputs — optically isolated, via PCF8574
2 relay outputs — high-current relay control, via PCF8574
2 DAC outputs — 0-10V analog, 12-bit (GP8403)
2 pulse counters — hardware interrupt-based
RS485 — half-duplex with automatic direction control
Modbus RTU — full Master and Slave implementation for PLC/SCADA
Push button — single / double / triple / long-press detection
2 PWM outputs — configurable frequency and resolution
Status LED — onboard indicator

Hardware specifications

Component	Model	I²C address	GPIO
Digital input expander	PCF8574	`0x3A`	—
Relay expander	PCF8574	`0x3C`	—
DAC	GP8403 (12-bit)	`0x58`	—
I²C bus	—	—	SDA 4, SCL 5
Pulse inputs	—	—	34, 35
Push button	—	—	16 (input pullup)
PWM outputs	LEDC	—	32, 33
Status LED	—	—	2
RS485	Serial2	—	RX 14, TX 13

Pin mapping

Digital Inputs  (PCF8574 @ 0x3A):  IN1–IN8 → P0–P7
Relay Outputs   (PCF8574 @ 0x3C):  RELAY1 → P3,  RELAY2 → P2
DAC Outputs     (GP8403  @ 0x58):  DAC_CH0, DAC_CH1 → 0–10V

Direct ESP32:
  GPIO 34 → PULSE1 (input only)    GPIO 33 → PWM2
  GPIO 35 → PULSE2 (input only)    GPIO  2 → Status LED
  GPIO 16 → Push Button (pullup)   GPIO 14 → RS485 RXD
  GPIO 32 → PWM1                   GPIO 13 → RS485 TXD
  GPIO  4 → I2C SDA                GPIO  5 → I2C SCL

Install the library

NI-EVALUATION_BOARD-V1

Board library, examples, and docs on GitHub.

Install NI-EVALUATION_BOARD-V1 from the Arduino Library Manager, or clone it into your libraries/ folder:

cd ~/Documents/Arduino/libraries/
git clone https://github.com/nikolaindustry/NI-EVALUATION_BOARD-V1.git

Dependencies:

PCF8574 by Renzo Mischianti (Library Manager)
ESP32 Arduino Core (Boards Manager)

Quick start

#include <NI-EVALUATION_BOARD-V1.h>

NIEvaluationBoardV1 board;

void setup() {
  Serial.begin(115200);
  if (board.begin()) Serial.println("Board initialized!");
}

void loop() {
  bool input1 = board.readDigitalInput(1);   // read input
  board.setRelay(1, input1);                  // drive relay 1
  board.setAnalogVoltage(0, 5.0);             // 5.0 V on DAC ch0
  unsigned long pulses = board.getPulseCount(1);
  delay(100);
}

begin() accepts optional RS485 baud, PWM frequency, and PWM resolution: begin(rs485Baud = 115200, pwmFreq = 5000, pwmResolution = 8).

API summary

Subsystem	Methods
Digital inputs	`readDigitalInput(channel)`
Relays	`setRelay(channel, on)`, `setAllRelays(on)`
DAC (0-10V)	`setAnalogVoltage(channel, volts)`, `setAnalogRaw(channel, value)`
Pulse counters	`getPulseCount(channel, resetAfterRead = false)`
PWM	`setPwmDuty(channel, duty)`, `configurePwm(freq, resolution)`
RS485	`rs485ReadLine(timeoutMs)` (+ direction handled automatically)
Modbus Master	`readCoils`, `readDiscreteInputs`, `readHoldingRegisters`, `readInputRegisters`, `writeSingleCoil`, `writeSingleRegister`, `writeMultipleCoils`, `writeMultipleRegisters`
Modbus Slave	`setSlaveAddress(addr)`, `process()`, `onReadCoil/onWriteCoil/onReadHoldingRegister/…` callbacks

Using it with Hyperwisor

The board library is independent, but it pairs with the Hyperwisor firmware SDK: read inputs / drive outputs with the board API, then push values to dashboard widgets and receive commands with the Hyperwisor library. The board repo includes a HypervisorIOT example showing the two together.

Firmware SDK

Connect the board to a dashboard.

The core loop

Push values, receive commands.

​Features

​Hardware specifications

​Pin mapping

​Install the library