Unit 8Servos2‑I2C Control Protocol (Firmware V2.0)

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1. Hardware Interface

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2. Register Overview

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3. I2C Read and Write Operations

3.1 Write Operation (Host Write)

Write format: [Register Address][Data Byte]

• Single-byte write: REG_ADDR + 1Byte Data
• Multi-byte continuous write: start register address + N consecutive data bytes, supporting batch writing to continuous register areas.

3.2 Read Operation (Host Read)

1. The host sends the 1-byte start register address
2. An I2C read is initiated, and the module returns the subsequent register data sequentially from that address
3. Reading a contiguous register area in one operation is supported.

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4. IO Mode Configuration Register 0x00

Each IO channel can be configured independently. Value definitions:

5. Pull-up/Pull-down Configuration Register 0x10

6. IO Level Registers

• 0x20(R): IO input status read, 1 is high level, 0 is low level.
• 0x30(R/W): IO output level setting, effective in OUTPUT mode only, 1 outputs high level, 0 outputs low level.

7. ADC Registers 0x40 / 0x50

The ADC is 12-bit, with a value range of 0 ~ 4095. 0x40: ADC low byte of each channel; 0x50: ADC high byte of each channel.

8. PWM Duty Cycle Register 0x60

• Value range: 0 ~ 100, representing a percentage.
• The PWM frequency is configured by the TIM2 / TIM3 registers.

9. RGB Control Registers 0x70 ~ 0xB0

• 0x70: bit5=1 triggers a WS2812 data refresh; bit[4‑0] sets the number of RGB LEDs.
• 0x80‑0xB0: RGB data, stored in B, G, R order, supporting up to 16 WS2812 LEDs.

10. Timer Frequency Registers 0xD0‑0xD3

11. UID Read 0xE0‑0xEB

• 12 bytes in total, read-only; the device unique hardware UID; supports continuous reading starting from any offset within the range.

12. Composite Register 0xF0 (Multiple Functions Multiplexed)

12.1 Voltage and Current Read (Read)

• Grove voltage, DC high voltage: unit mV
• Total current sampling: unit mA

Hardware detection indicator LED logic:

1. DC high voltage detection: when the DC voltage is higher than 8.5V, the red LED lights up.
2. Grove low voltage detection: when the Grove voltage is lower than 4.5V, the green LED lights up.

12.2 I2C Address Modification (Write)

Write to 0xF0:

• Offset: selector offset 0‑15
• Refresh bit write 1: refresh and update the I2C slave address;

12.3 Firmware Version Read (Read)

Read the corresponding offset of 0xF0 to return the Software Version.

12.4 Current I2C Address Read (Read)

Read the corresponding offset of 0xF0 to return the currently effective I2C slave address.

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13. Power-on Default State

1. All IOs default to INPUT mode with no pull-up/pull-down.
2. TIM2 / TIM3 default to 0; using Servo mode requires manually setting 50Hz.
3. The RGB refresh bit defaults to 0.
4. The I2C default base address is 0x25.

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14. Important Notes

1. Configuring Servo mode requires setting the corresponding timer frequency to 50HZ, otherwise PWM will not be output.
2. The PWM frequency in PWM and Servo modes is controlled separately by two timers: TIM2 controls GPIO0~GPIO3, TIM3 controls GPIO4~GPIO7.
3. When the DC voltage is higher than 8.5V, the small red LED lights up.
4. When the GROVE voltage is lower than 4.5V, the small green LED lights up.
5. RGB mode supports WS2812 RGB LEDs only.
6. I2C continuous read/write operations are only allowed within the "continuous read/write areas" marked in this document.
7. The module has no IRQ interrupt pin; all status is polled by the host through active I2C reads.

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15. Recommended Operation Order

1. Power on, then read the UID/version to verify I2C communication;
2. Set the IO modes according to your application (INPUT / OUTPUT / ADC / SERVOS / PWM / RGB);
3. If using Servo, configure TIM2 / TIM3 = 50Hz;
4. Configure the pull-up/pull-down, PWM duty cycle, and RGB parameters;
5. Read and write IO, ADC, and voltage/current;
6. To modify the I2C address: set the Offset and write Refresh=1 to refresh the address.