【BPI-CanMV-K230D-Zero开发板体验】+片温检测及显示

由于该开发板没配相应的显示器件，为进行显示需自行配置显示器件。

为了与其小巧的身材相匹配，就选取了一款I2C接口的0.91寸单色OLED屏与之配合。

要驱动显示屏，有2种方式，一种是采用模拟的方式来驱动，另一种则通过硬件的方式来驱动。

因厂家提供了一个OLED屏的基本驱动框架，为此可利用它来实现显示功能。

厂家提供的驱动程序框架为：

from machine import FPIOA, I2C
# use hardware i2c
if HARD_I2C:
    fpioa = FPIOA()
    fpioa.set_function(11, FPIOA.IIC2_SCL)
    fpioa.set_function(12, FPIOA.IIC2_SDA)
    i2c=I2C(2, freq = 400 * 1000)
    print(i2c.scan())
else:
    # use soft i2c
    i2c=I2C(5, scl = 11, sda = 12, freq = 400 * 1000)
    print(i2c.scan())
# SSD1306 I2C address (common values: 0x3C or 0x3D)
    OLED_I2C_ADDR = 0x3C
# Function to send a command to the SSD1306
def send_command(command):
    # 0x00 indicates we're sending a command (as opposed to data)
    i2c.writeto(OLED_I2C_ADDR, bytearray([0x00, command]))
# Function to send data (for pixel values) to the SSD1306

def send_data(data):
    # 0x40 indicates we're sending data (as opposed to a command)
    i2c.writeto(OLED_I2C_ADDR, bytearray([0x40] + data)) 

def send_data1(data):
    # 0x00 indicates we're sending data (as opposed to a command)
    i2c.writeto(OLED_I2C_ADDR, bytearray([0x40, data])) 

# SSD1306 Initialization sequence (based on datasheet)
def oled_init():
    send_command(0xAE)  # Display OFF
    send_command(0xA8)  # Set MUX Ratio
    send_command(0x3F)  # 64MUX
    send_command(0xD3)  # Set display offset
    send_command(0x00)  # Offset = 0
    send_command(0x40)  # Set display start line to 0
    send_command(0xA1)  # Set segment re-map (A1 for reverse, A0 for normal)
    send_command(0xC8)  # Set COM output scan direction (C8 for reverse, C0 for normal)
    send_command(0xDA)  # Set COM pins hardware configuration
    send_command(0x12)  # Alternative COM pin config, disable left/right remap
    send_command(0x81)  # Set contrast control
    send_command(0x7F)  # Max contrast
    send_command(0xA4)  # Entire display ON, resume to RAM content display
    send_command(0xA6)  # Set Normal display (A6 for normal, A7 for inverse)
    send_command(0xD5)  # Set oscillator frequency
    send_command(0x80)  # Frequency
    send_command(0x8D)  # Enable charge pump regulator
    send_command(0x14)  # Enable charge pump
    send_command(0xAF)  # Display ON 

# Function to clear the display (turn off all pixels)
def oled_clear():
    for page in range(0, 8):  # 8 pages in 64px tall screen
        send_command(0xB0 + page)  # Set page start address (0xB0 to 0xB7)
        send_command(0x00)  # Set low column address
        send_command(0x10)  # Set high column address
        send_data([0x00] * 128)

由程序可以得知，显示屏的引脚连接关系为：

SCL-------GPIO11

SDA------GPIO12

经程序运行，其测试效果如图1所示，说明它对显示屏驱动有效。

图1 连接与显示

图2 显示效果

在此基础上要实现显示功能，需配置字库和相应的显示函数。

其字库的存储结构为：

F8X16=[

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,#0

0x00,0x00,0x00,0xF8,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x33,0x30,0x00,0x00,0x00,#! 1

0x00,0x10,0x0C,0x06,0x10,0x0C,0x06,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,#" 2

... ...

}

参照清屏函数，实现符号显示的函数为：

def OLED_ShowCharm(x,y,chr):
    c=chr
    OLED_Set_Pos(x,y)
    i=0
    for i in range(8):
        u=F8X16[c*16+i]
        send_data([u]*1)
    OLED_Set_Pos(x,y+1)
    i=0
    for i in range(8):
        u=F8X16[c*16+i+8]
        send_data([u]*1)

有了字符显示函数，就可在其基础上再添加字符串显示函数和数值显示函数。

为检测片内温度，需导入os和machine，在OLED屏的配合下，实现片温显示的主程序为：

import os
import machine
 

# Initialize the OLED display
oled_init()
oled_clear()
OLED_ShowChar(8, 2, 52)
OLED_ShowChar(16, 5, 26)
OLED_ShowString(5,0,"CanMV-K230D")
while True:
    os.exitpoint()
    temp = machine.temperature()
    OLED_ShowNum(24,2,temp,2)
    time.sleep_ms(500)

在执行后，其显示效果如图3所示，由此看出其片内的温度还是比较高的，应为其配上散热器来降低芯片的温度。

图3 显示效果