I2C 概念
电子行业最常用的3种串行通讯协议：UART、SPI和I2C
在消费电子，工业电子等领域，会使用各种类型的芯片，如微控制器，电源管理，显示驱动，传感器，存储器，转换器等，他们有着不同的功能，有时需要快速的进行数据的交互，为了使用最简单的方式使这些芯片互联互通，于是I2C诞生了，I2C(Inter－Integrated Circuit)是一种通用的总线协议。它是由Philips(飞利浦)公司，现NXP(恩智浦)半导体开发的一种简单的双向两线制总线协议标准。
对于硬件设计人员来说，只需要2个管脚，极少的连接线和面积，就可以实现芯片间的通讯，对于软件开发者来说，可以使用同一个I2C驱动库，来实现实现不同器件的驱动，大大减少了软件的开发时间。极低的工作电流，降低了系统的功耗，完善的应答机制大大增强通讯的可靠性。
Firefly-RK3399
Firefly-RK3399 开发板上有 9 个片上 I2C 控制器，各个 I2C 的使用情况如下表：
配置 I2C
配置 I2C 可分为两大步骤：
- 定义和注册 I2C 设备
- 定义和注册 I2C 驱动
&i2c4 {
status = "okay";
i2c-scl-rising-time-ns = <475>;
i2c-scl-falling-time-ns = <26>;
24c02@50 {
compatible = "Atmel,24c02";
reg = <0x50>;
status = "okay";
};
gt9xx@5d{
status = "okay";
compatible = "goodix,gt9xx" ; // goodix 代表厂商汇顶科技，gt9xx触控型号
reg = < 0x5d >; // I2C 地址
pinctrl-names = "default";
pinctrl-0 = <>9xx_irq_gpio>; // 中断
touch-gpio = <&gpio4 29 IRQ_TYPE_EDGE_RISING>;
reset-gpio = <&gpio4 30 GPIO_ACTIVE_HIGH>; //复位
max-x = <800>;
max-y = <1280>;
tp-size = <970>;
};
};
&pinctrl {
gt9xx {
gt9xx_irq_gpio: gt9xx-irq-gpio {
rockchip,pins = <4 29 RK_FUNC_GPIO &pcfg_pull_up>;
};
};
};
原理图
小知识
I2C 未接触摸时 RST 引脚无电压, 区分哪个是RST，哪个是 IRQ
I2C0 PMIC
Silergy Corp.(中文音译：硅力杰(股)公司)系2008年2月7日成立于英属开曼群岛(以下简称「开曼」)之控股公司。硅力杰(股)公司及其子公司（以下简称「硅力杰」、「本公司」或「集团」）为一专业之模拟IC设计公司，为全球少数能生产小封装、高压大电流之IC设计公司之一。
&i2c0 {
vdd_cpu_b: syr827@40 {
compatible = "silergy,syr827";
reg = <0x40>;
vin-supply = <&vcc5v0_sys>;
regulator-compatible = "fan53555-reg";
pinctrl-0 = <&vsel1_gpio>;
vsel-gpios = <&gpio1 17 GPIO_ACTIVE_HIGH>; // CPU_B_SLEEP
regulator-name = "vdd_cpu_b";
regulator-min-microvolt = <712500>;
regulator-max-microvolt = <1500000>;
regulator-ramp-delay = <1000>;
fcs,suspend-voltage-selector = <1>;
regulator-always-on;
regulator-boot-on;
regulator-initial-state = <3>;
regulator-state-mem {
regulator-off-in-suspend;
};
};
vdd_gpu: syr828@41 {
compatible = "silergy,syr828";
reg = <0x41>;
vin-supply = <&vcc5v0_sys>;
regulator-compatible = "fan53555-reg";
pinctrl-0 = <&vsel2_gpio>;
vsel-gpios = <&gpio1 14 GPIO_ACTIVE_HIGH>; // GPU_SLEEP
regulator-name = "vdd_gpu";
regulator-min-microvolt = <712500>;
regulator-max-microvolt = <1500000>;
regulator-ramp-delay = <1000>;
fcs,suspend-voltage-selector = <1>;
regulator-always-on;
regulator-boot-on;
regulator-initial-state = <3>;
regulator-state-mem {
regulator-off-in-suspend;
};
};
rk808: pmic@1b {
compatible = "rockchip,rk808";
reg = <0x1b>;
interrupt-parent = <&gpio1>;
interrupts = <21 IRQ_TYPE_LEVEL_LOW>;
pinctrl-names = "default";
pinctrl-0 = <&pmic_int_l &pmic_dvs2>;
rockchip,system-power-controller;
wakeup-source;
#clock-cells = <1>;
clock-output-names = "xin32k", "rk808-clkout2";
vcc1-supply = <&vcc3v3_sys>;
vcc2-supply = <&vcc3v3_sys>;
vcc3-supply = <&vcc3v3_sys>;
vcc4-supply = <&vcc3v3_sys>;
vcc6-supply = <&vcc3v3_sys>;
vcc7-supply = <&vcc3v3_sys>;
vcc8-supply = <&vcc3v3_sys>;
vcc9-supply = <&vcc3v3_sys>;
vcc10-supply = <&vcc3v3_sys>;
vcc11-supply = <&vcc3v3_sys>;
vcc12-supply = <&vcc3v3_sys>;
vddio-supply = <&vcc1v8_pmu>;
regulators {
vdd_log: DCDC_REG1 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <750000>;
regulator-max-microvolt = <1350000>;
regulator-ramp-delay = <6001>;
regulator-name = "vdd_log";
regulator-state-mem {
regulator-on-in-suspend;
regulator-suspend-microvolt = <900000>;
};
};
vdd_cpu_l: DCDC_REG2 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <750000>;
regulator-max-microvolt = <1350000>;
regulator-ramp-delay = <6001>;
regulator-name = "vdd_cpu_l";
regulator-state-mem {
regulator-off-in-suspend;
};
};
vcc_ddr: DCDC_REG3 {
regulator-always-on;
regulator-boot-on;
regulator-name = "vcc_ddr";
regulator-state-mem {
regulator-on-in-suspend;
};
};
vcc_1v8: DCDC_REG4 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
regulator-name = "vcc_1v8";
regulator-state-mem {
regulator-on-in-suspend;
regulator-suspend-microvolt = <1800000>;
};
};
vcc1v8_dvp: LDO_REG1 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
regulator-name = "vcc1v8_dvp";
regulator-state-mem {
regulator-off-in-suspend;
};
};
vcc3v0_tp: LDO_REG2 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <3000000>;
regulator-max-microvolt = <3000000>;
regulator-name = "vcc3v0_tp";
regulator-state-mem {
regulator-off-in-suspend;
};
};
vcc1v8_pmu: LDO_REG3 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
regulator-name = "vcc1v8_pmu";
regulator-state-mem {
regulator-on-in-suspend;
regulator-suspend-microvolt = <1800000>;
};
};
vcc_sd: LDO_REG4 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <3000000>;
regulator-name = "vcc_sd";
regulator-state-mem {
regulator-on-in-suspend;
regulator-suspend-microvolt = <3000000>;
};
};
vcca3v0_codec: LDO_REG5 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <3000000>;
regulator-max-microvolt = <3000000>;
regulator-name = "vcca3v0_codec";
regulator-state-mem {
regulator-off-in-suspend;
};
};
vcc_1v5: LDO_REG6 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <1500000>;
regulator-max-microvolt = <1500000>;
regulator-name = "vcc_1v5";
regulator-state-mem {
regulator-on-in-suspend;
regulator-suspend-microvolt = <1500000>;
};
};
vcca1v8_codec: LDO_REG7 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
regulator-name = "vcca1v8_codec";
regulator-state-mem {
regulator-off-in-suspend;
};
};
vcc_3v0: LDO_REG8 {
regulator-always-on;
regulator-boot-on;
regulator-min-microvolt = <3000000>;
regulator-max-microvolt = <3000000>;
regulator-name = "vcc_3v0";
regulator-state-mem {
regulator-on-in-suspend;
regulator-suspend-microvolt = <3000000>;
};
};
vcc3v3_s3: SWITCH_REG1 {
regulator-always-on;
regulator-boot-on;
regulator-name = "vcc3v3_s3";
regulator-state-mem {
regulator-on-in-suspend;
};
};
vcc3v3_s0: SWITCH_REG2 {
regulator-always-on;
regulator-boot-on;
regulator-name = "vcc3v3_s0";
regulator-state-mem {
regulator-off-in-suspend;
};
};
};
};
};
Audio codec
&i2c1 {
status = "okay";
i2c-scl-rising-time-ns = <300>;
i2c-scl-falling-time-ns = <15>;
es8323: es8323@10 {
status = "disabled";
#sound-dai-cells = <0>;
compatible = "everest,es8323";
reg = <0x10>;
clocks = <&cru SCLK_I2S_8CH_OUT>;
clock-names = "mclk";
pinctrl-names = "default";
pinctrl-0 = <&i2s_8ch_mclk>;
spk-con-gpio = <&gpio1 13 GPIO_ACTIVE_HIGH>;
//hp-det-gpio = <&gpio0 12 GPIO_ACTIVE_LOW>;
};
es8316: es8316@10 {
status = "okay";
#sound-dai-cells = <0>;
compatible = "everest,es8316";
reg = <0x10>;
clocks = <&cru SCLK_I2S_8CH_OUT>;
clock-names = "mclk";
pinctrl-names = "default";
pinctrl-0 = <&i2s_8ch_mclk>;
spk-con-gpio = <&gpio4 4 GPIO_ACTIVE_HIGH>;
};
};
