Raspberry Pi I/O控制與感測器讀取
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This document provides an overview of Raspberry Pi I/O control and sensor reading. It discusses analog and digital signal processing, common sensors interfaces like I2C, SPI and UART. It also covers programming the GPIO, reading analog sensors using the MCP3008 ADC over SPI, and interfacing with digital sensors like the LIS3DH accelerometer over I2C. Code examples are provided to read sensors and display the data.
![GPIO
BCM2835 has 54 GPIO pins
The function select registers are used to define the
operation of the general-purpose I/O pins
There are 6 GPFSEL [5:0], each control the functions
of a block of 10 pins.
• The FSEL{n} field determines the functionality of the nth
GPIO pin.
9](https://image.slidesharecdn.com/04raspberrypiio-190114053237/85/Raspberry-Pi-I-O-9-320.jpg)
![需要I2C功能被開啓
sudo raspi-config 進入[Interfacing
Options]將I2C 開啓
lsmod 應顯示i2c_dev Driver 模組被載入
35](https://image.slidesharecdn.com/04raspberrypiio-190114053237/85/Raspberry-Pi-I-O-35-320.jpg)
![PMS3003 Serial Data Format
56
PM1 = data [5:4]
PM2.5 =data [7:6]
PM10 =data[9:8]](https://image.slidesharecdn.com/04raspberrypiio-190114053237/85/Raspberry-Pi-I-O-56-320.jpg)
Raspberry Pi I/O控制與感測器讀取
- 2. How to Get Sensor data ? Analog processing OPA/ Filter Sensor Voltage ADC 感應元件 CO2,CO, G-Sensor, Gryo Thermal, light …. 電能 Continuous Signal MCU I2C UART SPI USB MCU/ MPU Discrete Signal 動能、 化學能、 熱能、 光能 電阻 電流 電壓 演算法 處理 半導體物理、 材料、光電 元件、化工、 機械、… MCU/ MPU GPIO ADC
- 3. Raspberry Pi 2/3 I/O Pin out 3
- 4. Raspberry Pi I/O 子板 https://goo.gl/M7A6i9 4
- 6. GPIO – General Program Input/Output 注意輸出及輸入電壓準位 6 GPIO
- 7. Setup time & Hold Time 注意電位變化需時間 Selup Time Hold Time D lnput to Flop 7
- 9. GPIO BCM2835 has 54 GPIO pins The function select registers are used to define the operation of the general-purpose I/O pins There are 6 GPFSEL [5:0], each control the functions of a block of 10 pins. • The FSEL{n} field determines the functionality of the nth GPIO pin. 9
- 10. Set GPIO to Alternative Function 6.2 Alternative Function Assignments GPIO設好Function後, 開始進入Study 10
- 11. Register Map of special function 11
- 12. #define bit field for s/w 12
- 14. BCM2835 Low-Level I/O Library C library for Broadcom BCM 2835 as used in Raspberry Pi 用 mmap 方式 來實現user space 驅動程式, open (“dev/mem”,…) 範例程式目錄結構 ==> 14
- 15. Hands on cd pi-sensor/examples/blink ./build.sh ==> 產生執行檔 ./blink 看見LED 閃爍! build.sh (shell script) 使用gcc 編譯C程式, 如: gcc test.c -o test 15
- 16. Coding 16
- 17. 17
- 18. Lab: GPIO LED Blinking cd pi-sensor/examples/blink ./build.sh ./blink build.sh (shell script) 使用gcc 編 譯C程式, 如: gcc test.c -o test 18
- 19. Lab : PIR人體感測器 (GPIO Input) 有人經過 時Output訊號1 (感知紅外線波長變化) 19
- 20. Lab: 繼電器(Relay) 控制 動手做: 按下Button 時電燈開啓, 放開電燈關閉 20 pi-sensor/examples/blink/relay.c
- 22. PWM type Servo 伺服馬達 SG90 (180度Servo) 訊號定義 50Hz (20ms) period, pulse width range 1.0ms~2.0ms 橘 PWM 紅 5V 棕 GND
- 23. 1.0ms 角度0度, 1.5ms角度是90度, 2.0ms 角度是180度
- 24. Lab: PWM 程式: cd pi-sensore/examples/servo/sg90.c ./budild.sh; ./servo 24 bcm2835_gpio_fsel(PWM0,BCM2835_GPIO_FSEL_ALT5); //set gpio for PWM0 bcm2835_pwm_set_clock(1920); //set min frequence =19.2M/1920=10k bcm2835_pwm_set_mode(0,1,1); //(channel,PWM0 MSEN enable , PWM0 enable) bcm2835_pwm_set_range(0,200); //set period=20ms bcm2835_pwm_set_data(0,a); //a=1~20 0.1ms*a 0.1ms*200=20ms
- 25. 數位式感測器讀取
- 26. half-duplex, synchronous bus 它是一種廣播式的 bus 三種通訊速度 1) Standard is 100 Kbps 2) Fast-mode is 400 Kbps 3) high-speed mode supports speeds up to 3.4 Mbps supports 7-bit and 10-bit address • 0000xxx , 1111xxx有特殊用途 Master-slave communication support multi-master 26 What is I2C (Inter-IC) ?
- 27. 27 硬體接線
- 28. 28 Start and Stop conditions •
- 29. 29 硬體訊號
- 30. 30 Data format • Every byte put on the SDA line must be 8-bits long. • Each byte has to be followed by an acknowledge bit.
- 32. Lab : using LA to analyze the protocol ./eep w 0x50 0x10 0x55 ./eep r 0x50 0x10 32
- 33. apt-get install i2c-tools i2cdetect -y 1 => Scan I2C BUS 1 Using i2c-tools (open Source ) 33
- 34. 34 Using i2c-tools EEPROM read/write using i2cset/i2cget
- 35. 需要I2C功能被開啓 sudo raspi-config 進入[Interfacing Options]將I2C 開啓 lsmod 應顯示i2c_dev Driver 模組被載入 35
- 36. I2C Interface G-Sensor (STMicro LIS3DH)
- 37. Lab : MEMS digital output motion sensor STMicro (LIS3DH) SPI/I2C Interface The LIS3DH has dynamically user-selectable full scales of ±2g/±4g/±8g/±16g Measuring accelerations with output data rates from 1 Hz to 5.3 kHz. 37 16bits represents ±2g : 18193 2g1g-1g-2g 36383-18193-36383 0 平放時1g, 2g必須產生外力
- 38. G Sensor-Acceleration Meter 可以知道X,Y,Z的加速度變化(加速度的單位:g , 9.8m/s2) 在不同的傾斜角度會輸出不同G值, 故可以用來量測物體的 傾斜角度 38
- 39. 傾斜角度 39
- 40. LIS3DH Register Map Slave Address 0x19 40
- 42. Read/Write Operation 42 SAD+R/W’: Slave Address+ Read/Write’ SUB: 8-bit sub-address (SUB) : internal register address in chip If the MSB of the SUB field is ‘1’, the SUB allow multiple data read/writes.
- 43. Protocol for LIS3DH 43 MAK is Master acknowledge and NMAK is No Master Acknowledge 0x32 0x28 0x33 X_L 0x32 0xA8
- 44. Code Snippet for Read: 程式碼位置: pi-sensorexamplesLIS3DHI2C_Profile.c
- 45. Lab: G-sensor app on Raspberry Pi cd pi-sensor/examples/LIS3DH chmod +x build.sh ; ./build.sh; ./GSensor
- 46. Lab : OLED 輸出 SSD1306Z : I2C Interface , 128x64, 0.94吋 46 ,
- 47. UART Interface Air Quality sensors
- 48. 48
- 49. Dust sensors 懸浮微粒 (Particulate Matter) :漂浮在空氣中 類似灰塵的粒狀物 粒徑小於或等於 2.5 微米（μm）的粒子，就稱為 PM2.5，通稱細懸浮微粒。PM 2.5 的直徑還不到 人的頭髮絲粗細的 1/28 PM1.0, PM 2.5, PM10.0 依據空氣中不同的懸浮顆粒個數，推算灰 塵的質量濃度，單位 μg/m3 49
- 50. AQI (Air Quality Index) 50 關於 行政院環保署細懸浮微粒管制 http://air.epa.gov.tw/Public/suspended_particles.aspx
- 54. UART 接線方式 54 /dev/ttyUSB0 9600, 8N1 PL2303 (usb-to-serial ) PMS3003 腳位 White: RX Green: TX Black: GND Red: 5V
- 55. Capture serial data 55 每一秒會輸出 24 byte serial data In Linux: cat /dev/ttyUSB0 | hexdump
- 56. PMS3003 Serial Data Format 56 PM1 = data [5:4] PM2.5 =data [7:6] PM10 =data[9:8]
- 57. 解析 24 byte serial data 57 42 4D 00 14 00 02 00 03 00 03 00 02 00 03 00 03 00 C2 00 02 97 00 02 0E 20byte data 含checksum 00 02: PM1.0 : 2ug/m3 00 03: PM2.5 : 3ug/m3 00 03: PM10 : 3ug/m3 ChceckSum (42 4D 00 14 00 02 00 03 00 03 00 02 00 03 00 03 00 C2 00 02 97 00 ) = 0x020E=52610
- 58. Demo code pip install pyserial cd pi-sensor/examples/pms3003 python dump-serial.py python g3.py 58
- 60. ADC (MCP3008) SPI Interface 60 Raspberry Pi MCP3008 SPI Analog signal
- 61. SPI 線路 61 SPI 為一個Ring 結構:要讀資料,必送資料 {dummy byte}
- 62. CPOL: rest state of clock (high or low) CPHA: First or second SCLK transition CPOL,CPHA 用來決定latch 資料的時間點 SPI 模式 62
- 63. ADC (MCP3008) 2.7V 4-Channel/8-Channel 10-Bit A/D Converters with SPI Serial Interface 4 pseudo-differential input pairs or 8 single-ended inputs 63
- 64. 64
- 65. LSB: 最小刻度 VREF determines the analog input voltage range 65
- 67. 67
- 68. Lab : 讀取ADC 光敏電阻 讀取ADC channel 0 68
- 70. USB Webcam
- 71. apt-get install libgd2-noxpm-dev ./configure make make install 71
- 72. What is the GD library? https://libgd.github.io GD is an open source code library for the dynamic creation of images by programmers. GD is written in C, and "wrappers" are available for Perl, PHP and other languages. GD creates PNG, JPEG, GIF, WebP, XPM, BMP images, among other formats. 72
- 73. 73
- 74. References BCM2835 ARM Peripherals Manual 艾鍗 Pi 3 Shield 電路圖 24LC16 Datasheet MCP3008 Datasheet LIS3DH Datasheet 74
Editor's Notes
- #7: Examples (drivers/char/it_dio.c)