諾基亞5110 LCD初始化問題

我想通過SPI協議將諾基亞5110 LCD連接到BeagleBone Black Rev-C。諾基亞5110 LCD初始化問題

的連接完全一樣的6頁上顯示： Nokia5110-BeagleBone Black Connections

我寫了一個C當量的Arduino的飛利浦PCD8544代碼（諾基亞3310）驅動程序。我在哪裏輸出所需的GPIO端口並通過SPI接口發送命令和數據。

我成功安裝並運行Adafruit的的蟒蛇庫： Adafruit Nokia LCD

我的問題是

我有一個奇怪的問題，當我第一次，然後運行這個Python代碼我的C代碼，代碼工作完美！但是，如果我在python代碼之前運行我的C代碼，我沒有輸出。邏輯說，python 代碼必須初始化我在我的代碼中缺少的東西。

下面是如何初始化LCD：

fd_spi_dev = open(device, O_RDWR); 
//set mode 
mode = SPI_MODE_0; 
ioctl(fd_spi_dev, SPI_IOC_WR_MODE, &mode); 
ioctl(fd_spi_dev, SPI_IOC_RD_MODE, &mode); 
//set max bitrate 
speed = 4000000; 
ioctl(fd_spi_dev, SPI_IOC_RD_MAX_SPEED_HZ, &speed); 
ioctl(fd_spi_dev, SPI_IOC_WR_MAX_SPEED_HZ, &speed); 
// set an msb first 
lsbsetting = 0; 
ioctl(fd_spi_dev, SPI_IOC_WR_LSB_FIRST, &lsbsetting); 
// set bits per word 
bits = 8; 
ioctl(fd_spi_dev, SPI_IOC_WR_BITS_PER_WORD, &bits); 
ioctl(fd_spi_dev, SPI_IOC_RD_BITS_PER_WORD, &bits); 

lcd_write_cmd(0x21); // LCD extended commands 
lcd_write_cmd(0xB8); // set LCD Vop (contrast) 
lcd_write_cmd(0x04); // set temp coefficient 
lcd_write_cmd(0x14); // set biad mode 1:40 
lcd_write_cmd(0x20); // LCD basic commands 
lcd_write_cmd(0x09); // LCD all segments on 
/* I am expecting to see all segments lit here */ 
sleep(5); 
lcd_write_cmd(0x0C); // LCD normal video 

void lcd_write_cmd(uint8_t cmd) { 
    uint8_t *tx = &cmd; 
    uint8_t rx; 
    uint32_t len = 1; 

    struct spi_ioc_transfer tr = { 
     .tx_buf = (uint32_t)tx, 
     .rx_buf = (uint32_t)&rx, 
     .len = len, 
     .delay_usecs = delay, 
     .speed_hz = speed, 
     .bits_per_word = bits, 
     .cs_change = 1, 
    }; 

    size = write(fd_dc_val, "0", 1); 
    size = write(fd_cs_val, "0", 1); 

    ioctl(fd_spi_dev, SPI_IOC_MESSAGE(1), &tr); 

    write(fd_cs_val, "1", 1); 
}

我在嵌入式編程新手。我將不勝感激任何幫助。謝謝。

來源

2015-11-14 nachiketkulk