tuyaopen-onchip-i2c

name	tuyaopen/onchip-i2c
description	On-chip I2C master for TuyaOpen using the tkl_i2c API: mux SCL/SDA, init the bus, and send/receive to a 7-bit slave address. I2C、IIC、I2C总线、传感器、SCL、SDA、从机地址、tkl_i2c、读传感器。
when_to_use	Use when the user wants to talk to an I2C device (sensor, EEPROM, etc.) as bus master: send a register/command and read bytes back.
id	onchip-i2c
surfaces	["embedded"]
tags	["i2c","iic","sensor","bus","on-chip","tkl_i2c"]

TuyaOpen On-Chip I2C (master)

On-chip — no Kconfig, no TDD

• Platform-provided. Do NOT write CONFIG_ENABLE_I2C. No app_default.config change needed.
• No board_register_hardware(). Call tkl_i2c_* directly with TUYA_I2C_NUM_<n>.
• Confirm which I2C bus + SCL/SDA pins + the device's 7-bit address with the user; record as onchip:i2c<n> in used-peripherals.json.

Platform spec — read, don't hardcode

.tuyaopen/ide/platform.json → peripherals.i2c.spec: ports[].pinGroups give each bus's SCL/SDA pin options (single group → default pins, no mux; multiple → pick one and mux — see below), speed the valid bus speeds, addrWidth the address widths. Read these for the chosen bus instead of assuming pins/speeds.

Init + transfer

Default case: do NOT call tkl_io_pinmux_config. Use the bus's default SCL/SDA pins — just tkl_i2c_init() and transfer. Add pin mux only when you deliberately route SCL/SDA to a non-default pin group (and only then #include "tkl_pinmux.h").

#include "tal_api.h"
#include "tkl_i2c.h"

#define I2C_PORT   TUYA_I2C_NUM_0
#define DEV_ADDR   0x44            /* 7-bit slave address */

void app_i2c_init(void)
{
    TUYA_IIC_BASE_CFG_T cfg = {
        .role       = TUYA_IIC_MODE_MASTER,
        .speed      = TUYA_IIC_BUS_SPEED_100K,
        .addr_width = TUYA_IIC_ADDRESS_7BIT,
    };
    tkl_i2c_init(I2C_PORT, &cfg);
}

Read a register (write pointer, then repeated-start read):

OPERATE_RET app_i2c_read_reg(uint8_t reg, uint8_t *buf, uint16_t len)
{
    /* write register pointer (no stop), then read */
    OPERATE_RET rt = tkl_i2c_master_send(I2C_PORT, DEV_ADDR, &reg, 1, FALSE);
    if (rt != OPRT_OK) return rt;
    return tkl_i2c_master_receive(I2C_PORT, DEV_ADDR, buf, len, FALSE);
}

Alternate pins only (omit entirely for default pins):

#include "tkl_pinmux.h"
tkl_io_pinmux_config(TUYA_IO_PIN_15, TUYA_IIC0_SCL);
tkl_io_pinmux_config(TUYA_IO_PIN_16, TUYA_IIC0_SDA);

API Reference

Function	Description
tkl_i2c_init(port, &cfg)	cfg.role (TUYA_IIC_MODE_MASTER), cfg.speed (TUYA_IIC_BUS_SPEED_100K / _400K), cfg.addr_width (TUYA_IIC_ADDRESS_7BIT)
tkl_i2c_master_send(port, addr, data, len, stop)	Send to 7-bit addr; stop=FALSE keeps the bus for a repeated start
tkl_i2c_master_receive(port, addr, data, len, stop)	Read len bytes from addr
tkl_i2c_deinit(port)	Release the bus

tkl_io_pinmux_config(PIN, TUYA_IIC<n>_SCL / TUYA_IIC<n>_SDA) maps the bus pins.

Troubleshooting

Symptom	Likely cause	Fix
All transfers fail / NAK	Wrong 7-bit address, or no pull-ups	Verify address (datasheet); I2C needs SCL/SDA pull-ups
Bus never starts on non-default pins	Alternate SCL/SDA group not muxed	tkl_io_pinmux_config for SCL+SDA before tkl_i2c_init (default pins need none)
Reads return stale/garbage	Sent stop between write-reg and read	Use stop=FALSE on the register write (repeated start)

Reference example

SDK: examples/peripherals/i2c/ (i2c_scan; sht3x_4x_sensor — pin mux, master send/receive).