PIC-IoT WA Development Board ( EV54Y39A) is an AWS pre-provisioned rapid prototyping IoT development board released by Microchip.
Built on the classic three-tier IoT architecture consisting of main MCU + secure crypto chip + Wi-Fi wireless module, it enables sensor data upload to the cloud right out of the box. It serves as a standardized evaluation platform for low-power IoT end devices from prototype verification to mass production deployment.
Schematic Diagram of PIC-IoT WA
(Images sourced from Microchip)
1. Core On-Board Chips
表格
| Part Number | Function & Role | Remarks |
|---|---|---|
| PIC24FJ128GA705 (16-bit MCU) | Main controller responsible for overall logic scheduling, ADC sampling, peripheral protocol processing and Wi-Fi data interaction | 128 KB Flash, 16 KB RAM, featuring XLP ultra-low-power core |
| ATWINC1510 Wi‑Fi Module | Establishes 2.4 GHz Wi-Fi connection, interfaces with the MCU via SPI bus and transmits data to the cloud over MQTT | On-board PCB antenna, pre-certified for 802.11b/g/n |
| ATECC608A | Hardware security crypto chip (I2C interface); securely stores AWS device credentials and performs ECC signature authentication | Private keys are non-extractable; core component to prevent IoT device cloning |
| MCP9808 | High-precision I2C temperature sensor for ambient temperature measurement | Used for temperature data cloud upload in the official demo |
| MCP73871 | Li-ion battery charge/discharge management IC; handles charging of 3.7 V Li-Po batteries and power path switching | Automatic power switching between MicroUSB and lithium battery |
| MIC33050 | LDO voltage regulator; converts 5 V input to stable 3.3 V system supply | Supplies power to the entire MCU, crypto chip and all peripherals |
| PKoB4 nano (On-Board Debugger) | All-in-one programming and debugging unit integrating firmware download, CDC virtual serial port and basic logic analyzer | No external emulator required |
| TEMT6000 Phototransistor | Voltage-divider ambient light sensor connected to an ADC pin for luminance measurement | — |
On-Board Human-Machine Interface Components
- 2 user pushbuttons: SW0 → RA7, SW1 → RA10; internal MCU pull-up resistors enabled, active-low trigger
- 4 status LEDs for Wi-Fi & cloud links
- RC5: Wi-Fi connection status indicator
- RC4: Cloud connection status indicator
- RC3: Data transmit/receive indicator
- RB4: Fault/error indicator
- Charge indicator: Dual-color CHGSTAT LED; red = charging, green = fully charged
- MicroUSB port: Triple function for power supply, debug serial communication and firmware flashing
- JST connector: Interface for 3.7 V lithium polymer battery
2. Full Pin Definition of Dual-Row Expansion Headers (Left Header | Right Header)
Left Header (MCU Pins + Power Supplies + Communication Buses)
表格
| Silkscreen Label | MCU Pin | Description |
|---|---|---|
| ADC AIN7 | RB14 | 12-bit ADC analog input, compatible with external voltage-type sensors |
| RESET | RB15 | MCU hardware reset pin, active-low reset |
| SPI CS | RA0 | SPI chip select; multiplexed with the ATWINC1510 chip select signal |
| SPI SCK | RA1 | SPI clock line |
| SPI MISO | RB0 | SPI master-in slave-out |
| SPI MOSI | RB1 | SPI master-out slave-in |
| 3.3V | N/A | Regulated system power output; maximum load limited by the on-board LDO rating |
| GND | N/A | Common power ground |
Right Header (General Peripheral Buses + Power Supplies)
表格
| Silkscreen Label | MCU Pin | Description |
|---|---|---|
| Timer/PWM | RC6 | Timer / PWM output; for motor driving or LED dimming |
| Interrupt | RB7 | External interrupt input pin |
| UART RX | RB6 | Hardware UART receive pin |
| UART TX | RB5 | Hardware UART transmit pin |
| I2C SCL | RB8 | I2C clock line (shared with on-board MCP9808 and ATECC608A) |
| I2C SDA | RB9 | I2C data line |
| 5.0V | N/A | Direct pass-through 5 V from MicroUSB; cuttable via 0 Ω resistor for compatibility with low-voltage mikroBUS peripherals |
| GND | N/A | Common ground |
Bus Notes
The I2C bus (RB8/RB9) is shared by the on-board MCP9808 temperature sensor and ATECC608A crypto chip; no bus conflict occurs when adding external I2C devices.
The SPI bus is dedicated to the on-board Wi-Fi module; extra chip select signals are required when connecting external SPI peripherals.
3. Power Supply Architecture
- USB-powered mode: 5 V input via MicroUSB. One branch is stepped down to 3.3 V by MIC33050 to power the whole board; another branch charges the external Li-Po battery through MCP73871.
- Battery-powered mode: A 3.7 V lithium battery is plugged into the JST connector. MCP73871 automatically switches to battery power, and the LDO outputs 3.3 V for normal board operation.
- 5 V / 3.3 V isolation rule: The 5 V pin on the right header is directly fed from USB, while the 3.3 V pin is sourced from the on-board MIC33050. These two voltage rails must never be shorted together.
4. Key Pin Usage Guidelines for Development
- Analog sampling: AIN7 (RB14) supports external voltage-divider analog sensors such as NTC thermistors and additional photoresistors, paired with the integrated 12-bit MCU ADC.
- Serial debug: Hardware UART (RB5=TX, RB6=RX) can interface with RS485 transceivers or Bluetooth modules.
- I2C expansion: RB8 (SCL) + RB9 (SDA) work with most I2C sensors (temperature & humidity, gas sensors) and are fully compatible with mikroBUS modules.
- PWM driving: RC6 PWM pin is suitable for LED dimming and small servo motor control; RB7 external interrupt pin connects to trigger devices including PIR motion sensors and vibration switches.
Related Documents
Related Products
- PIC-IoT WA Development Board ( EV54Y39A)
Related Articles
- Get Started Quickly with the PIC-IoT WA Development Board – A Quick Start Guide
- Get Started Quickly with the PIC-IoT WA Development Board – On-Board Resource Breakdown
- Get Started Quickly with the PIC-IoT WA Development Board – Power Supply Configuration Guide
- Get Started Quickly with the PIC-IoT WA Development Board – Online Programming Guide
- Get Started Quickly with the PIC-IoT WA Development Board – CDC Virtual Serial Port