[原创] SAM4E LED0亮度随光照自动调节（TWI读bh1750）

梭罗瓦尔登 2015-2-28 13:32 楼主

现在的智能手机其实都带光强传感器，大体是这样的，在光照强的地方，屏幕也亮，因此有利于看清楚屏幕上的字，之前发过呼吸灯的例子，这里我再加上BH1750来模拟智能手机的这项功能，只是做个小demo，也有很多不好的地方，大哥们就多指正，我利用ASF里的TWI例程加以修改，使之能够读出BH1750传感器的数据并转换成光强强度，然后根据光强设置PWM的占空比，来设置一下亮度，原理就是这样。贴一下代码，注释都在代码里，有问题及时回帖交流，不完善的及时指正。

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#include //******************************************** 20150127修改*********************************************//
#include
#include "conf_board.h"
//****************************************
uint32_t light=0;
#define PERIOD_VALUE 547
#define BREATH_INTERVAL_PERIOD 100 /*LED暗下来一段时间*/
#define STRING_EOL "\r"
#define STRING_HEADER "-- EDBG TWI Information Interface Example --\r\n" \
"-- "BOARD_NAME" --\r\n" \
"-- Compiled: "__DATE__" "__TIME__" --"STRING_EOL
/** TWI Bus Clock 400kHz */
#define TWI_CLK 400000
/** EDBG TWI interface address */
#define EDBG_ADDRESS 0xD1;
/** Request token of EDBG TWI information interface */
#define EDBG_EXTEN_BOARDS_TOKEN 0x75;
#define EDBG_KIT_DATA_TOKEN 0xD2;
#define BH1750 0x5C
/** I2C related structure */
twi_options_t opt;
twi_packet_t packet_rx;
twi_packet_t packet_tx;
/* Number of times to try to send packet if failed. */
#define TIMEOUT 10
/** Read buffer */
uint8_t read_buffer[1];
/** Extension board info structure*/
uint8_t extension_map[2];
uint8_t extension_info[64];
uint16_t minimum_voltage;
uint16_t maximum_voltage;
uint16_t minimum_current;
#ifdef CONF_KIT_DATA_EXIST
/** Kit data structure*/
uint8_t kit_data[256];
#endif
/**
* \brief Function for show the extension boards information
*
*/
/*[中断处理程序]*/
void PWM_Handler(void)
{
static uint32_t ul_duty = 0; /* PWM 占空比*/
static uint8_t fade_in = 1; /* LED 淡入标志 */
static uint8_t dark_period = 0; /* LED 完全暗下来时间 */
/* 读取PWM_ISR1寄存器，同时可以拉低中断 */
uint32_t events = PWM->PWM_ISR1;
/* 先确定是否是指定的中断，PWM_ISR1_CHID2表示PWM_ISR1寄存器的CHID0位*/
if ((events & PWM_ISR1_CHID2) != 0)
{
if (dark_period != 0)
{
dark_period--;
return;
}
/* 设置新的占空比 */
PWM->PWM_CH_NUM[2].PWM_CDTYUPD = PWM_CDTY_CDTY(light/100);
}
}
void ConfigPIO(void)
{
/* 引脚由外设控制 */
PIOD->PIO_PDR = PIO_PD22;
/* 选择外设 */
/* PIOD选择外设D（将影响PD所有引脚） */
PIOD->PIO_ABCDSR[0] = 0;
PIOD->PIO_ABCDSR[1] = 0;
}
/*配置PWM*/
void ConfigPWM(void)
{
/* 外设时钟启用,PWM的ID大于31，需要在PMC_PCER1中启用*/
PMC->PMC_PCER1 = 1 << (ID_PWM - 32);
/* 禁用通道2，以进行配置 */
PWM->PWM_DIS = PWM_DIS_CHID2;
/* 配置通道2,计数器时钟选择为32分频，周期左对齐，先输出低电平，不使用死区发生器。
这里需要用到较高频率的时钟，所以选择使用主时钟经32分频后的时钟（12.5 kHz）。计数器周期为400，即输出脉冲频率为125000/400 = 312.5 Hz。*/
PWM->PWM_CH_NUM[2].PWM_CMR =PWM_CMR_CPRE_MCK_DIV_32;
/* 启用中断 */
PWM->PWM_IER1 = PWM_IER1_CHID2;
PWM->PWM_CH_NUM[2].PWM_CPRD = PWM_CPRD_CPRD(PERIOD_VALUE); /* 设置周期 */
PWM->PWM_CH_NUM[2].PWM_CDTY = PWM_CDTY_CDTY(0); /* 设置占空比*/
/* 使能中断 */
NVIC_ClearPendingIRQ(PWM_IRQn);
NVIC_SetPriority(PWM_IRQn, 0);
NVIC_EnableIRQ(PWM_IRQn);
/* 使能 PWM */
PWM->PWM_ENA = PWM_ENA_CHID2;
}
static void show_extension_boards_information(void)
{
//uint8_t request_token = EDBG_EXTEN_BOARDS_TOKEN;
uint32_t timeout = 0;
uint8_t board_num = 0;
uint8_t i;
uint8_t request_token[5] ={0x01,0x10,0,0,0};//地址意义看上面的宏定义
uint8_t dat[2]={0x01,0x10}; //初始值
for(i=0;i<2;i++)
{ packet_tx.chip = BH1750;
packet_tx.addr_length = 1;
packet_tx.addr[0] = request_token[i];
packet_tx.buffer = dat+i;
packet_tx.length = 1;
while (twi_master_write(EDBG_I2C_MODULE, &packet_tx) != TWI_SUCCESS) {
/* Increment timeout counter and check if timed out. */
if (timeout++ == TIMEOUT) {
puts("timeout!\n");
return;
}
}
}
return;
}
#ifdef CONF_KIT_DATA_EXIST
/*
uint32_t GetData(uint8_t* REG_Address)
{
uint8_t H,L;
H=*REG_Address;
L=*(REG_Address+1);
return (H<<8)+L; //合成数据
}
*/
static void bh1750_init(void)
{
uint8_t dat[2]={0x01,0x11}; //command 0x01 power on 0x10 start converting
uint8_t timeout=0;
uint8_t send_count;
for(send_count=0;send_count<=1;send_count++)//这里要看BH1750的数据手册，它把第二个字节的数据当命令，所以我们先发俩字节来初始化它
{
packet_tx.chip = BH1750;
packet_tx.buffer = dat+send_count;
packet_tx.length = 1;
while (twi_master_write(EDBG_I2C_MODULE, &packet_tx) != TWI_SUCCESS) {
// Increment timeout counter and check if timed out.
if (timeout++ == TIMEOUT) {
puts("timeout!!!!!!!!!!!\n");
return;
}
}
delay_ms(10);
}
}
static void show_light_data(uint32_t *light)
{
uint8_t g_data[6]={0x00,0x00};
uint8_t timeout=0;
uint32_t g_data_32[3]={0x00,0x00};
float lux;
packet_rx.chip = BH1750;
packet_rx.addr_length = 1;
packet_rx.addr[0] = 0x23;//数据从0x23读出
packet_rx.buffer =g_data;
packet_rx.length = 2;//要读两个字节
while (twi_master_read(EDBG_I2C_MODULE, &packet_rx) != TWI_SUCCESS) {
/* Increment timeout counter and check if timed out. */
if (timeout++ == TIMEOUT) {
printf("\read error \n");
return;
}
}
g_data_32[0]=(g_data[0]<<8)+g_data[1];//data processing
lux=(float)g_data_32[0]/1.2;
/** show kit data */
printf("\rLIGHT == %d \n LUX == %d \n",g_data_32[0],(uint)lux);//串口打印光强数据
*light=(uint32_t)lux;//数据传出去，来调节PWM从而控制led0的亮度
}
#endif
/**
* \brief Function for configuring I2C master module
*
* This function will configure the I2C master module with
* the SERCOM module to be used and pinmux settings
*/
static void configure_i2c_master(void)
{
/* Enable the peripheral clock for TWI */
pmc_enable_periph_clk(EDBG_I2C_MODULE_ID);
/* Configure the options of TWI driver */
opt.master_clk = sysclk_get_cpu_hz();
opt.speed = TWI_CLK;
if (twi_master_init(EDBG_I2C_MODULE, &opt) != TWI_SUCCESS) {
puts("-E-\tTWI master initialization failed.\r");
while (1) {
/* Capture error */
}
}
}
static void configure_console(void)
{
const usart_serial_options_t uart_serial_options = {
.baudrate = CONF_UART_BAUDRATE,
.paritytype = CONF_UART_PARITY
};
/* Configure console UART. */
sysclk_enable_peripheral_clock(CONSOLE_UART_ID);
stdio_serial_init(CONF_UART, &uart_serial_options);
}
/**
* \brief Main application
*/
int main(void)
{
/* Initialize the SAM system */
sysclk_init();
/* Initialize the board */
board_init();
/*Configure UART console.*/
configure_console();
/* Configure the I2C master module */
configure_i2c_master();
/* Output example information */
puts(STRING_HEADER);
/* Show the extension boards information */
WDT->WDT_MR = WDT_MR_WDDIS;
ConfigPWM();
ConfigPIO();
//while (1);
while(1)
{
#ifdef CONF_KIT_DATA_EXIST
bh1750_init();//初始化之后一定要等120ms
delay_ms(120);
show_light_data(&light);
#endif
}
while (1)
{}
}