触摸屏
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2022-03-22 16:42:53
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触摸屏
首先置位相应时钟
adc_clock = clk_get(NULL, "adc");
if (!adc_clock) {
printk(KERN_ERR "failed to get adc clock source\n");
return -ENOENT;
}
clk_enable(adc_clock);
触摸屏接口模式:
1、Normal Conversion Mode
2、Separate X/Y position conversion Mode
3、Auto(Sequential) X/Y position conversion Mode
4、Waiting for Interrupt Mode
5、Standby Mode
//触摸屏寄存器
struct s3c_ts_regs {
unsigned long adccon;
unsigned long adctsc;
unsigned long adcdly;
unsigned long adcdat0;
unsigned long adcdat1;
unsigned long adcupdn;
};
static volatile struct s3c_ts_regs *s3c_ts_regs;
模式设置:
等待中断等效图
等待松开,等待按下模式
static void enter_wait_pen_down_mode(void)
{
s3c_ts_regs->adctsc = 0xd3;
}
static void enter_wait_pen_up_mode(void)
{
s3c_ts_regs->adctsc = 0x1d3;
}
x/y转化模式:
!Alt text
static void enter_measure_xy_mode(void)
{
s3c_ts_regs->adctsc = (1<<3)|(1<<2);
}
启动ADC控制器
static void start_adc(void)
{
s3c_ts_regs->adccon |= (1<<0);
}
中断函数
static irqreturn_t pen_down_up_irq(int irq, void *dev_id)
{
if (s3c_ts_regs->adcdat0 & (1<<15))
{
printk("pen up\n");
enter_wait_pen_down_mode();
}
else
{
//printk("pen down\n");
//enter_wait_pen_up_mode();
enter_measure_xy_mode();
start_adc();
}
return IRQ_HANDLED;
}
措施4:软件过滤
static int s3c_filter_ts(int x[], int y[])
{
#define ERR_LIMIT 10
int avr_x, avr_y;
int det_x, det_y;
avr_x = (x[0] + x[1])/2;
avr_y = (y[0] + y[1])/2;
det_x = (x[2] > avr_x) ? (x[2] - avr_x) : (avr_x - x[2]);
det_y = (y[2] > avr_y) ? (y[2] - avr_y) : (avr_y - y[2]);
if ((det_x > ERR_LIMIT) || (det_y > ERR_LIMIT))
return 0;
avr_x = (x[1] + x[2])/2;
avr_y = (y[1] + y[2])/2;
det_x = (x[3] > avr_x) ? (x[3] - avr_x) : (avr_x - x[3]);
det_y = (y[3] > avr_y) ? (y[3] - avr_y) : (avr_y - y[3]);
if ((det_x > ERR_LIMIT) || (det_y > ERR_LIMIT))
return 0;
return 1;
}
定时器函数
static void s3c_ts_timer_function(unsigned long data)
{
if (s3c_ts_regs->adcdat0 & (1<<15))
{
/* 已经松开 */
enter_wait_pen_down_mode();
}
else
{
/* 测量X/Y坐标 */
enter_measure_xy_mode();
start_adc();
}
}
adc中断:
static irqreturn_t adc_irq(int irq, void *dev_id)
{
static int cnt = 0;
static int x[4], y[4];
int adcdat0, adcdat1;
/* 优化措施2: 如果ADC完成时, 发现触摸笔已经松开, 则丢弃此次结果 */
adcdat0 = s3c_ts_regs->adcdat0;
adcdat1 = s3c_ts_regs->adcdat1;
if (s3c_ts_regs->adcdat0 & (1<<15))
{
/* 已经松开 */
cnt = 0;
enter_wait_pen_down_mode();
}
else
{
// printk("adc_irq cnt = %d, x = %d, y = %d\n", ++cnt, adcdat0 & 0x3ff, adcdat1 & 0x3ff);
/* 优化措施3: 多次测量求平均值 */
x[cnt] = adcdat0 & 0x3ff;
y[cnt] = adcdat1 & 0x3ff;
++cnt;
if (cnt == 4)
{
/* 优化措施4: 软件过滤 */
if (s3c_filter_ts(x, y))
{
printk("x = %d, y = %d\n", (x[0]+x[1]+x[2]+x[3])/4, (y[0]+y[1]+y[2]+y[3])/4);
}
cnt = 0;
enter_wait_pen_up_mode();
/* 启动定时器处理长按/滑动的情况 */
mod_timer(&ts_timer, jiffies + HZ/100);
}
else
{
enter_measure_xy_mode();
start_adc();
}
}
return IRQ_HANDLED;
}
初始化
static int s3c_ts_init(void)
{
//1、分配一个input_dev结构体
s3c_ts_dev = input_allocate_device();
//2、设置
//2.1 能产生哪类事件
set_bit(EV_KEY,s3c_ts_dev->evbit);
set_bit(EV_ABS,s3c_ts_dev->evbit);
//2.2 能产生这类事件的哪些事件
set_bit(BTN_TOUCH, s3c_ts_dev->keybit);
input_set_abs_params(s3c_ts_dev, ABS_X, 0, 0x3FF, 0, 0);
input_set_abs_params(s3c_ts_dev, ABS_Y, 0, 0x3FF, 0, 0);
input_set_abs_params(s3c_ts_dev, ABS_PRESSURE, 0, 1, 0, 0);
//3、注册
input_register_device(s3c_ts_dev);
//4、硬件相关的操作
/* 4.1 使能时钟(CLKCON[15]) */
adc_clock = clk_get(NULL, "adc");
if (!adc_clock) {
printk(KERN_ERR "failed to get adc clock source\n");
return -ENOENT;
}
clk_enable(adc_clock);
/* 4.2 设置S3C2440的ADC/TS寄存器 */
s3c_ts_regs = ioremap(0x58000000, sizeof(struct s3c_ts_regs));
/* bit[14] : 1-A/D converter prescaler enable
* bit[13:6]: A/D converter prescaler value,
* 49,ADCCLK=PCLK/(49+1)=50MHz/(49+1)=1MHz
* bit[0]: A/D conversion starts by enable. 先设为0
*/
s3c_ts_regs->adccon = (1<<14)|(49<<6);
request_irq(IRQ_TC, pen_down_up_irq, IRQF_SAMPLE_RANDOM, "ts_pen", NULL);
request_irq(IRQ_ADC, adc_irq, IRQF_SAMPLE_RANDOM, "adc", NULL);
//优化错施1:
//设置ADCDLY为最大值, 这使得电压稳定后再发出IRQ_TC中断
s3c_ts_regs->adcdly = 0xffff;
//优化措施5: 使用定时器处理长按,滑动的情况
init_timer(&ts_timer);
ts_timer.function = s3c_ts_timer_function;
add_timer(&ts_timer);
//等待按下
enter_wait_pen_down_mode();
return 0;
}
硬件相关操作时
有数据产生时,input_even
从input_device链表中找到,,调用input_handle.handler中的event函数。
比对过程:
根据input_handler中的id_table与input_dev中的id.bustype
看下evdev_handler
input_event(input,type,button->code,!!state);
上报完事件还要上报个同步事件。
input_sync(input);
input_sync()
static inline void input_sync(struct input_dev *dev)
{
input_event(dev,EV_SYN,SYN_REPORT,0);
//表示这个事件已经上报完毕
}
static struct input_handler evdev_handler = {
.event = evdev_event,
.connect = evdev_connect,
.disconnect = evdev_disconnect,
.fops = &evdev_fops,
.minor = EVDEV_MINOR_BASE,
.name = "evdev",
.id_table = evdev_ids,
};
看下 evdev_ids
static const struct input_device_id evdev_ids[] = {
{ .driver_info = 1 }, /* Matches all devices */
{ }, /* Terminating zero entry */
};
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