在 jetson orin nx 上 使用 libgpiod 库操作 gpio
在 jetson orin nx 上 使用 libgpiod 库操作 gpio
Ubuntu 22.04 使用较新的内核（5.15+），默认已弃用旧的 sysfs GPIO接口（
CONFIG_GPIO_SYSFS），改用新的字符设备接口（CONFIG_GPIO_CDEV）。所以/sys/class/gpio并不存在，新内核推荐使用 libgpiod 工具操作GPIO，有命令行工具，也有 c 语言操作接口。下面就以jetson orin nx为例讲述一下如何使用。
安装 libgpiod 命令行工具
一般情况我只会用到 gpioinfo，用来查找 chip 和 line 的编号。
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# 安装
sudo apt install gpiod
# 查看可用 GPIO 芯片
gpiodetect
# 查看 GPIO 引脚信息（例如芯片0）
gpioinfo 0
# 控制 GPIO
sudo gpioset 0 17=1
# 设置io电平，并保持，直到ctrl + c或者 回车
sudo gpioset -m wait gpiochip0 43=0
# 查看 gpio 的电平状态
cat /sys/kernel/debug/gpio
通过引脚对照表找到引脚对应的 GPIO 编号
由此可得:
| 引脚 | gpio 编号 |
|---|---|
| 7 | GPIO09 |
| 15 | GPIO12 |
| 29 | GPIO01 |
| 31 | GPIO11 |
| 32 | GPIO07 |
| 33 | GPIO13 |
通过 GPIO 编号找到对应的 PORT
下载 Jetson_Orin_NX_and_Orin_Nano_series_Pinmux_Config_Template.xlsm表格，查找 PORT。 
由此可得:
| 引脚 | gpio 编号 | PORT |
|---|---|---|
| 7 | GPIO09 | PAC.06 |
| 15 | GPIO12 | PN.01 |
| 29 | GPIO01 | PQ.05 |
| 31 | GPIO11 | PQ.06 |
| 32 | GPIO07 | PG.06 |
| 33 | GPIO13 | PH.00 |
通过 PORT 找到 Line
执行 gpioinfo 命令
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gpioinfo
gpiochip0 - 164 lines:
line 0: "PA.00" "regulator-vdd-3v3-sd" output active-high [used]
line 1: "PA.01" unused input active-high
line 2: "PA.02" unused input active-high
line 3: "PA.03" unused input active-high
line 4: "PA.04" unused input active-high
line 5: "PA.05" unused input active-high
line 6: "PA.06" unused input active-high
line 7: "PA.07" unused input active-high
line 8: "PB.00" unused input active-high
line 9: "PC.00" unused input active-high
line 10: "PC.01" unused input active-high
line 11: "PC.02" unused input active-high
line 12: "PC.03" unused input active-high
line 13: "PC.04" unused input active-high
line 14: "PC.05" unused input active-high
line 15: "PC.06" unused input active-high
line 16: "PC.07" unused input active-high
line 17: "PD.00" unused input active-high
line 18: "PD.01" unused input active-high
line 19: "PD.02" unused input active-high
line 20: "PD.03" unused input active-high
line 21: "PE.00" unused input active-high
line 22: "PE.01" unused input active-high
line 23: "PE.02" unused input active-high
line 24: "PE.03" unused input active-high
line 25: "PE.04" unused input active-high
line 26: "PE.05" unused input active-high
line 27: "PE.06" unused input active-high
line 28: "PE.07" unused input active-high
line 29: "PF.00" unused input active-high
line 30: "PF.01" unused input active-high
line 31: "PF.02" unused input active-high
line 32: "PF.03" unused input active-high
line 33: "PF.04" unused input active-high
line 34: "PF.05" unused input active-high
line 35: "PG.00" "Force Recovery" input active-low [used]
line 36: "PG.01" unused input active-high
line 37: "PG.02" unused input active-high
line 38: "PG.03" unused input active-high
line 39: "PG.04" unused input active-high
line 40: "PG.05" unused input active-high
line 41: "PG.06" unused input active-high
line 42: "PG.07" unused input active-high
line 43: "PH.00" unused input active-high
line 44: "PH.01" unused input active-high
line 45: "PH.02" unused input active-high
line 46: "PH.03" "camera-control-output-low" output active-high [used]
line 47: "PH.04" unused input active-high
line 48: "PH.05" unused input active-high
line 49: "PH.06" unused output active-high
line 50: "PH.07" unused input active-high
line 51: "PI.00" unused input active-high
line 52: "PI.01" unused input active-high
line 53: "PI.02" unused input active-high
line 54: "PI.03" unused input active-high
line 55: "PI.04" unused input active-high
line 56: "PI.05" kernel input active-high [used]
line 57: "PI.06" unused input active-high
line 58: "PJ.00" unused input active-high
line 59: "PJ.01" unused input active-high
line 60: "PJ.02" unused input active-high
line 61: "PJ.03" unused input active-high
line 62: "PJ.04" unused input active-high
line 63: "PJ.05" unused input active-high
line 64: "PK.00" unused input active-high
line 65: "PK.01" unused input active-high
line 66: "PK.02" unused input active-high
line 67: "PK.03" unused input active-high
line 68: "PK.04" unused output active-high
line 69: "PK.05" unused output active-high
line 70: "PK.06" unused input active-high
line 71: "PK.07" unused input active-high
line 72: "PL.00" unused input active-high
line 73: "PL.01" unused input active-high
line 74: "PL.02" unused input active-high
line 75: "PL.03" unused input active-high
line 76: "PM.00" kernel input active-high [used]
line 77: "PM.01" unused input active-high
line 78: "PM.02" unused input active-high
line 79: "PM.03" unused input active-high
line 80: "PM.04" unused input active-high
line 81: "PM.05" unused input active-high
line 82: "PM.06" unused input active-high
line 83: "PM.07" unused input active-high
line 84: "PN.00" unused input active-high
line 85: "PN.01" unused input active-high
line 86: "PN.02" unused input active-high
line 87: "PN.03" unused input active-high
line 88: "PN.04" unused input active-high
line 89: "PN.05" unused input active-high
line 90: "PN.06" unused input active-high
line 91: "PN.07" unused input active-high
line 92: "PP.00" unused input active-high
line 93: "PP.01" unused input active-high
line 94: "PP.02" unused input active-high
line 95: "PP.03" unused input active-high
line 96: "PP.04" unused input active-high
line 97: "PP.05" unused input active-high
line 98: "PP.06" unused input active-high
line 99: "PP.07" unused input active-high
line 100: "PQ.00" unused input active-high
line 101: "PQ.01" unused input active-high
line 102: "PQ.02" unused input active-high
line 103: "PQ.03" unused output active-high
line 104: "PQ.04" unused input active-high
line 105: "PQ.05" unused input active-high
line 106: "PQ.06" unused input active-high
line 107: "PQ.07" unused input active-high
line 108: "PR.00" unused input active-high
line 109: "PR.01" unused input active-high
line 110: "PR.02" unused input active-high
line 111: "PR.03" unused input active-high
line 112: "PR.04" unused input active-high
line 113: "PR.05" unused input active-high
line 114: "PX.00" kernel input active-high [used]
line 115: "PX.01" kernel input active-high [used]
line 116: "PX.02" unused input active-high
line 117: "PX.03" unused input active-high
line 118: "PX.04" unused input active-high
line 119: "PX.05" unused input active-high
line 120: "PX.06" unused input active-high
line 121: "PX.07" unused input active-high
line 122: "PY.00" unused input active-high
line 123: "PY.01" unused input active-high
line 124: "PY.02" unused input active-high
line 125: "PY.03" unused input active-high
line 126: "PY.04" unused input active-high
line 127: "PY.05" unused input active-high
line 128: "PY.06" unused input active-high
line 129: "PY.07" unused input active-high
line 130: "PZ.00" unused input active-high
line 131: "PZ.01" "interrupt" input active-high [used]
line 132: "PZ.02" unused input active-high
line 133: "PZ.03" unused input active-high
line 134: "PZ.04" unused input active-high
line 135: "PZ.05" unused input active-high
line 136: "PZ.06" unused input active-high
line 137: "PZ.07" unused input active-high
line 138: "PAC.00" unused output active-high
line 139: "PAC.01" unused input active-high
line 140: "PAC.02" unused input active-high
line 141: "PAC.03" unused input active-high
line 142: "PAC.04" unused input active-high
line 143: "PAC.05" unused input active-high
line 144: "PAC.06" unused input active-high
line 145: "PAC.07" unused input active-high
line 146: "PAD.00" unused input active-high
line 147: "PAD.01" unused input active-high
line 148: "PAD.02" unused input active-high
line 149: "PAD.03" unused input active-high
line 150: "PAE.00" unused input active-high
line 151: "PAE.01" unused input active-high
line 152: "PAF.00" unused input active-high
line 153: "PAF.01" unused input active-high
line 154: "PAF.02" unused input active-high
line 155: "PAF.03" unused input active-high
line 156: "PAG.00" unused input active-high
line 157: "PAG.01" unused input active-high
line 158: "PAG.02" unused input active-high
line 159: "PAG.03" unused input active-high
line 160: "PAG.04" unused input active-high
line 161: "PAG.05" unused input active-high
line 162: "PAG.06" unused input active-high
line 163: "PAG.07" unused input active-high
gpiochip1 - 32 lines:
line 0: "PAA.00" unused input active-high
line 1: "PAA.01" unused input active-high
line 2: "PAA.02" unused input active-high
line 3: "PAA.03" unused input active-high
line 4: "PAA.04" unused output active-high
line 5: "PAA.05" "regulator-vdd-3v3-pcie" output active-high [used]
line 6: "PAA.06" unused input active-high
line 7: "PAA.07" unused input active-high
line 8: "PBB.00" unused input active-high
line 9: "PBB.01" unused input active-high
line 10: "PBB.02" unused input active-high
line 11: "PBB.03" unused output active-high
line 12: "PCC.00" unused output active-high
line 13: "PCC.01" unused output active-high
line 14: "PCC.02" unused output active-high
line 15: "PCC.03" "mux" output active-high [used]
line 16: "PCC.04" unused input active-high
line 17: "PCC.05" unused input active-high
line 18: "PCC.06" unused input active-high
line 19: "PCC.07" unused input active-high
line 20: "PDD.00" unused input active-high
line 21: "PDD.01" unused input active-high
line 22: "PDD.02" unused input active-high
line 23: "PEE.00" unused input active-high
line 24: "PEE.01" unused input active-high
line 25: "PEE.02" unused input active-high
line 26: "PEE.03" unused input active-high
line 27: "PEE.04" "Power" input active-low [used]
line 28: "PEE.05" unused input active-high
line 29: "PEE.06" unused input active-high
line 30: "PEE.07" unused input active-high
line 31: "PGG.00" unused input active-high
由此可得:
| 引脚 | gpio 编号 | PORT | CHIP | LINE |
|---|---|---|---|---|
| 7 | GPIO09 | PAC.06 | gpiochip0 | 144 |
| 15 | GPIO12 | PN.01 | gpiochip0 | 85 |
| 29 | GPIO01 | PQ.05 | gpiochip0 | 105 |
| 31 | GPIO11 | PQ.06 | gpiochip0 | 106 |
| 32 | GPIO07 | PG.06 | gpiochip0 | 41 |
| 33 | GPIO13 | PH.00 | gpiochip0 | 43 |
编写 c++ 代码操作 GPIO
- 安装 lbgpdio 库
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sudo apt install libgpiod-dev
参考文档 传送门
参考代码
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#include <gpiod.h> // sudo apt install libgpiod-dev
#include <cstdint>
#include <string>
#include <tuple>
#include <string>
#include <map>
namespace GpioHelper {
using Pin = uint32_t;
using Chip = std::string;
using Line = uint32_t;
const uint32_t DirectionOut = 0;
const uint32_t DirectionIn = 1;
auto get_pin_map() -> std::map<Pin, std::tuple<Chip, Line>> {
return {
{7, {"gpiochip0", 144}}, // GPIO09 PAC.06
{15, {"gpiochip0", 85}}, // GPIO12 PN.01
{29, {"gpiochip0", 105}}, // GPIO01 PQ.05
{31, {"gpiochip0", 106}}, // GPIO11 PQ.06
{32, {"gpiochip0", 41}}, // GPIO07 PG.06
{33, {"gpiochip0", 43}} // GPIO13 PH.00
};
}
} // namespace GpioHelper
int main() {
// 以开发板引脚 7 为例：
GpioHelper::Pin pin(7);
struct gpiod_chip *pchip;
struct gpiod_line *pline;
// 打开 chip
auto map = get_pin_map();
auto chip = std::get<0>(map[pin]);
auto line = std::get<1>(map[pin]);
pchip = gpiod_chip_open_by_name(chip.c_str());
if (!pchip) {
std::cout << "Failed to open GPIO chip\n";
return -1;
}
// 获取 GPIO Line
pline = gpiod_chip_get_line(pchip, line_num);
if (!pline) {
gpiod_chip_close(pchip);
std::cout << "Failed to get GPIO line\n";
return -1;
}
// 设置 GPIO 方向
auto ret = gpiod_line_request_output(pline, "gpio", GpioHelper::DirectionOut);
if (ret < 0) {
gpiod_line_release(pline);
gpiod_chip_close(pchip);
std::cout << "Failed to set GPIO direction\n";
return -1;
}
// 设置高电平
gpiod_line_set_value(pline, 1);
// 读取电平
int val = gpiod_line_get_value(pline);
std::cout << val << "\n";
// 设置低电平
gpiod_line_set_value(pline, 0);
// 读取电平
val = gpiod_line_get_value(pline);
std::cout << val << "\n";
// 释放资源
if (pline) {
gpiod_line_release(pline);
}
if (pchip) {
gpiod_chip_close(pchip);
}
return 0;
}
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