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XPT2046 LLD Major Update

Browse source 
Added 7 point median filtering to reduce noise
TOUCHPADDriver structure now encapsulates the IRQ pin, so removed
the TP_CS_ and TP_IRQ_ macros
Added generic tp_lld_read_value method to read any ADC channel from
the XPT2046, this includes on-chip temperature sensor and VBAT input
Improved SPI bus sharing, with the optional TOUCHPAD_SPI_PROLOGUE and
TOUCHPAD_SPI_EPILOGUE macros
This commit is contained in:
Kumar Abhishek 2012-08-16 15:14:16 +05:30
parent 7334da9f7f
commit a9beec902d
2 changed files with 172 additions and 46 deletions
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155
drivers/touchpad/XPT2046/touchpad_lld.c
View file

@ -36,9 +36,6 @@
/* Driver local definitions. */
/*===========================================================================*/
#define TP_CS_HIGH palSetPad(TP_CS_PORT, TP_CS)
#define TP_CS_LOW palClearPad(TP_CS_PORT, TP_CS)
#ifdef UNUSED
#elif defined(__GNUC__)
# define UNUSED(x) UNUSED_ ## x __attribute__((unused))
@ -52,13 +49,15 @@
/* Driver exported variables. */
/*===========================================================================*/
#if !defined(__DOXYGEN__)
TOUCHPADDriver Touchpad;
#endif
/*===========================================================================*/
/* Driver local variables. */
/*===========================================================================*/
#if !defined(__DOXYGEN__)
/* Local copy of the current touchpad driver */
static const TOUCHPADDriver *tpDriver;
static uint16_t sampleBuf[7];
#endif
/*===========================================================================*/
/* Driver local functions. */
@ -79,30 +78,104 @@
*
* @notapi
*/
void tp_lld_init(TOUCHPADDriver *tp) {
spiStart(tp->spid, tp->spicfg);
void tp_lld_init(const TOUCHPADDriver *tp) {
tpDriver=tp;
if (tpDriver->direct_init)
spiStart(tpDriver->spip, tpDriver->spicfg);
}
/**
* @brief Reads a conversion from the touchpad
*
* @param[in] cmd The command bits to send to the touchpad
*
* @return The read value 12-bit right-justified
*
* @note This function only reads data, it is assumed that the pins are
* configured properly and the bus has been acquired beforehand
*
* @notapi
*/
uint16_t tp_lld_read_value(uint8_t cmd) {
static uint8_t txbuf[3]={0};
static uint8_t rxbuf[3]={0};
uint16_t ret;
txbuf[0]=cmd;
spiExchange(tpDriver->spip, 3, txbuf, rxbuf);
ret = (rxbuf[1] << 5) | (rxbuf[2] >> 3);
return ret;
}
/**
* @brief 7-point median filtering code for touchpad samples
*
* @note This is an internally used routine only.
*
* @notapi
*/
static void tp_lld_filter(void) {
uint16_t temp;
int i,j;
for (i=0; i<4; i++) {
for (j=i; j<7; j++) {
if (sampleBuf[i] > sampleBuf[j]) {
/* Swap the values */
temp=sampleBuf[i];
sampleBuf[i]=sampleBuf[j];
sampleBuf[j]=temp;
}
}
}
}
/**
* @brief Reads out the X direction.
*
* @note The samples are median filtered for greater noise reduction
*
* @notapi
*/
uint16_t tp_lld_read_x(void) {
uint8_t txbuf[1];
uint8_t rxbuf[2];
uint16_t x;
int i;
txbuf[0] = 0xd0;
TP_CS_LOW;
spiSend(&SPID1, 1, txbuf);
spiReceive(&SPID1, 2, rxbuf);
TP_CS_HIGH;
#if defined(SPI_USE_MUTUAL_EXCLUSION)
spiAcquireBus(tpDriver->spip);
#endif
x = rxbuf[0] << 4;
x |= rxbuf[1] >> 4;
TOUCHPAD_SPI_PROLOGUE();
palClearPad(tpDriver->spicfg->ssport, tpDriver->spicfg->sspad);
return x;
/* Discard the first conversion - very noisy and keep the ADC on hereafter
* till we are done with the sampling. Note that PENIRQ is disabled.
*/
tp_lld_read_value(0xD1);
for (i=0;i<7;i++) {
sampleBuf[i]=tp_lld_read_value(0xD1);
}
/* Switch on PENIRQ once again - perform a dummy read */
tp_lld_read_value(0xD0);
palSetPad(tpDriver->spicfg->ssport, tpDriver->spicfg->sspad);
TOUCHPAD_SPI_EPILOGUE();
#if defined(SPI_USE_MUTUAL_EXCLUSION)
spiReleaseBus(tpDriver->spip);
#endif
/* Find the median - use selection sort */
tp_lld_filter();
return sampleBuf[3];
}
/*
@ -111,20 +184,38 @@ uint16_t tp_lld_read_x(void) {
* @notapi
*/
uint16_t tp_lld_read_y(void) {
uint8_t txbuf[1];
uint8_t rxbuf[2];
uint16_t y;
int i;
txbuf[0] = 0x90;
TP_CS_LOW;
spiSend(&SPID1, 1, txbuf);
spiReceive(&SPID1, 2, rxbuf);
TP_CS_HIGH;
#if defined(SPI_USE_MUTUAL_EXCLUSION)
spiAcquireBus(tpDriver->spip);
#endif
y = rxbuf[0] << 4;
y |= rxbuf[1] >> 4;
TOUCHPAD_SPI_PROLOGUE();
palClearPad(tpDriver->spicfg->ssport, tpDriver->spicfg->sspad);
return y;
/* Discard the first conversion - very noisy and keep the ADC on hereafter
* till we are done with the sampling. Note that PENIRQ is disabled.
*/
tp_lld_read_value(0x91);
for (i=0;i<7;i++) {
sampleBuf[i]=tp_lld_read_value(0x91);
}
/* Switch on PENIRQ once again - perform a dummy read */
tp_lld_read_value(0x90);
palSetPad(tpDriver->spicfg->ssport, tpDriver->spicfg->sspad);
TOUCHPAD_SPI_EPILOGUE();
#ifdef SPI_USE_MUTUAL_EXCLUSION
spiReleaseBus(tpDriver->spip);
#endif
/* Find the median - use selection sort */
tp_lld_filter();
return sampleBuf[3];
}
/* ---- Optional Routines ---- */
@ -137,7 +228,7 @@ uint16_t tp_lld_read_y(void) {
* @notapi
*/
uint8_t tp_lld_irq(void) {
return (!palReadPad(TP_IRQ_PORT, TP_IRQ));
return (!palReadPad(tpDriver->tpIRQPort, tpDriver->tpIRQPin));
}
#endif

63
include/touchpad_lld.h
View file

@ -49,41 +49,76 @@
#define TOUCHPAD_HAS_PRESSURE FALSE
#endif
#ifndef TOUCHPAD_SPI_PROLOGUE
#define TOUCHPAD_SPI_PROLOGUE()
#endif
#ifndef TOUCHPAD_SPI_EPILOGUE
#define TOUCHPAD_SPI_EPILOGUE()
#endif
/*===========================================================================*/
/* Driver types. */
/*===========================================================================*/
typedef struct TOUCHPADDriver TOUCHPADDriver;
typedef struct _TOUCHPADDriver TOUCHPADDriver;
/**
* @brief Structure representing a Touchpad driver.
*/
struct TOUCHPADDriver {
/*
* @brief Pointer to SPI driver.
*/
SPIDriver *spid;
struct _TOUCHPADDriver {
/*
* @brief Pointer to SPI driver.
* @note SPI driver must be enabled in mcuconf.h and halconf.h
*/
SPIDriver *spip;
/*
* @brief SPI configuration.
*/
SPIConfig *spicfg;
/*
* @brief Pointer to the SPI configuration structure.
* @note The lowest possible speed ~ 1-2MHz is to be used, otherwise
* will result in a lot of noise
*/
const SPIConfig *spicfg;
/*
* @brief Touchscreen controller TPIRQ pin GPIO port
*/
ioportid_t tpIRQPort;
/*
* @brief Touchscreen controller TPIRQ GPIO pin
* @note The interface is polled as of now, interrupt support is
* to be implemented in the future.
*/
ioportmask_t tpIRQPin;
/*
* @brief Initialize the SPI with the configuration struct given or not
* If TRUE, spiStart is called by the init, otherwise not
* @note This is provided in such a case when SPI port is being shared
* across multiple peripherals, so not to disturb the SPI bus.
* You can use TOUCHPAD_SPI_PROLOGUE() and TOUCHPAD_SPI_EPILOGUE()
* macros to change the SPI configuration or speed before and
* after using the touchpad. An example case would be sharing the
* bus with a fast flash memory chip.
*/
bool_t direct_init;
};
/*===========================================================================*/
/* External declarations. */
/*===========================================================================*/
#if !defined(__DOXYGEN__)
extern TOUCHPADDriver Touchpad;
#endif
#ifdef __cplusplus
extern "C" {
#endif
/* Core functions */
void tp_lld_init(TOUCHPADDriver *tp);
void tp_lld_init(const TOUCHPADDriver *tp);
uint16_t tp_lld_read_value(uint8_t cmd);
uint16_t tp_lld_read_x(void);
uint16_t tp_lld_read_y(void);