🛠 Advanced I/O Control and Power Management on M5Stamp Timer Power 2

Objectives

Learn to configure the 5 programmable IOs (GPIO, ADC, PWM) of the M5Stamp Timer Power 2 to interface with sensors or displays. Understand the interaction between power outputs (3V3_DCDC_OUT, 3V3_LDO_OUT) and the PY32L020 microcontroller logic. Optimize power consumption by leveraging deep sleep modes (6.72uA off, 12.27uA standby) with interrupt-based wake-up.

Materials Needed

• M5Stamp Timer Power 2 Module (SKU S021)
• USB-C programming cable
• Analog sensor (e.g., thermistor) or digital (e.g., push button)
• RGB LED or small OLED screen
• DC 5V power supply or 3.7V LiPo battery
• Arduino IDE or M5Burner software

Steps

1. Environment Setup: Install PY32L020 support in Arduino IDE. Select the « M5Stamp Timer Power 2 » board and the correct serial port.
2. Power Output Initialization: Before using IOs, enable voltage rails if needed via internal registers or dedicated pins. Note that 3V3_DCDC_OUT provides 0.6A while 3V3_LDO_OUT offers 0.4A. Ensure total load does not exceed these limits.
3. GPIO Configuration: The 5 IOs are multiplexed. For a button, configure a pin as INPUT_PULLUP. For an LED, use OUTPUT. For an analog sensor, select the appropriate ADC channel.

// Example GPIO configuration
pinMode(IO_PIN_BTN, INPUT_PULLUP);
pinMode(IO_PIN_LED, OUTPUT);
analogReadResolution(12); // If supported

1. PWM Implementation: Use a PWM-compatible pin to control LED brightness or motor speed. Check the default timer frequency of the PY32L020.

analogWrite(IO_PIN_PWM, 128); // 50% duty cycle

1. Interrupt and Sleep Management: Configure a pin for falling-edge interrupt mode. Before entering sleep, save IO states and disable unnecessary clocks.

attachInterrupt(digitalPinToInterrupt(IO_PIN_BTN), wakeCallback, FALLING);
// Code to enter Deep Sleep mode
py32l020_enter_sleep();

1. Data Reading: Read ADC values or GPIO states after wake-up. Wake-up can be scheduled (timer) or external (IRQ). Standby consumption is then 12.27uA at 4.2V.

Verification

• Measure voltage on EXT_5V_INOUT to confirm power supply.
• Verify that the LED turns on/off according to PWM commands.
• Use a multimeter to measure current in off mode (expected ~6.72uA).
• Press the button to verify module wake-up.

To Go Further

Explore I2C communication (address 0x6E) to read M5PM1 chip parameters. Adjust charging current (650mA or 180mA) via dedicated pins to optimize battery life. Test stability of PY_3V3 outputs under variable load to avoid voltage drops.