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0023_Sense_HAT.md

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Sense HAT

Sense HAT使用方法

参考文档

RPI 4插入Sense HAT无法使用

为什么树莓派会自动加载Sense HAT的设备树及驱动

  • Part 3: Using Device Trees on Raspberry Pi
    • In order to manage Device Tree and overlays, the loader supports a number of new config.txt directives.
    • The loader will also search for an attached HAT with a programmed EEPROM, and load the supporting overlay from there; this happens without any user intervention.
    • 自动加载驱动：/etc/modules

rpi-sense firmware

  • 使用raspi-config打开I2C、SPI接口；
  • sudo apt-get update
  • sudo apt-get install sense-hat
    • 示例程序：/usr/src/sense-hat/examples
  • sudo apt-get install gcc-avr avr-libc avrdude
  • sudo reboot
  • cd ~
  • git clone https://github.com/raspberrypi/rpi-sense
  • make
  • make flash

AVR Assembler

lsm9ds1 i2c device

  • https://github.com/FrankBau/raspi-repo-manifest/wiki/device-tree#device-tree-overlays-sense-hat 
    // rpi-sense HAT
/dts-v1/;
/plugin/;

/ {
	compatible = "brcm,bcm2708", "brcm,bcm2709";

	fragment@0 {
		target = <&i2c1>;
		__overlay__ {
			#address-cells = <1>;
			#size-cells = <0>;
			status = "okay";

			rpi-sense@46 {
				compatible = "rpi,rpi-sense";
				reg = <0x46>;
				keys-int-gpios = <&gpio 23 1>;
				status = "okay";
			};

			lsm9ds1-magn@1c {
				compatible = "st,lsm9ds1-magn";
				reg = <0x1c>;
				status = "okay";
			};

			lsm9ds1-accel6a {
				compatible = "st,lsm9ds1-accel";
				reg = <0x6a>;
				status = "okay";
			};

			lps25h-press@5c {
				compatible = "st,lps25h-press";
				reg = <0x5c>;
				status = "okay";
			};

			hts221-humid@5f {
				compatible = "st,hts221-humid";
				reg = <0x5f>;
				status = "okay";
			};
		};
	};
};
  • 检查设备 
    root@raspberrypi:/sys/bus/i2c/devices# ls
1-001c  1-0046  1-005c  1-005f  1-006a  i2c-1
root@raspberrypi:/sys/bus/i2c/devices# cat 1-001c/name
lsm9ds1-magn
root@raspberrypi:/sys/bus/i2c/devices# cat 1-0046/name
rpi-sense
root@raspberrypi:/sys/bus/i2c/devices# cat 1-005c/name
lps25h-press
root@raspberrypi:/sys/bus/i2c/devices# cat 1-005f/name
hts221-humid
root@raspberrypi:/sys/bus/i2c/devices# cat 1-006a/name
lsm9ds1-accel
  • /proc/device-tree/soc/i2c@7e804000/lsm9ds1-magn@1c
  • cat /proc/device-tree/soc/i2c@7e804000/lsm9ds1-magn@1c/compatible
    • "st,lsm9ds1-magn"
  • diff from ST linux driver 
    diff --git a/st_magn/st_mag3d_i2c.c b/st_magn/st_mag3d_i2c.c
index e8c7d0a..4741f3b 100644
--- a/st_magn/st_mag3d_i2c.c
+++ b/st_magn/st_mag3d_i2c.c
@@ -66,7 +66,7 @@ static const struct of_device_id st_mag3d_id_table[] = {
                .compatible = "st,lis3mdl_magn",
        },
        {
-               .compatible = "st,lsm9ds1_magn",
+               .compatible = "st,lsm9ds1-magn",
        },
        {},
 };
  • lsm9ds1 driver
  • 确认设备节点：/dev/iio:device0
  • sysfs没有trigger 
    pi@raspberrypi:~ $ ls /sys/bus/iio/devices/
iio:device0
pi@raspberrypi:~ $ ls /sys/bus/iio/devices/iio\:device0
current_timestamp_clock  in_magn_x_raw    in_magn_y_raw    in_magn_z_raw    name     power               sampling_frequency_available  uevent
dev                      in_magn_x_scale  in_magn_y_scale  in_magn_z_scale  of_node  sampling_frequency  subsystem
  • iio-tools
    • ./iio_generic_buffer -N 0 -g 
      iio device number being used is 0
trigger-less mode selected
Problem reading scan element information
diag /sys/bus/iio/devices/iio:device0
    • 没有生成/sys/bus/iio/devices/iio:device0/scan_elements导致的，经分析代码发现，由于没有使用中断导致没有注册buffer导致的；

Sense HAT API