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HAL_PX4: use write() to /dev/pwm_output for servo output

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this lowest the cost of PWM output a lot, but relies on the new I2C
based IO firmware
This commit is contained in:
Andrew Tridgell 2013-01-25 19:16:28 +11:00
parent 9178022a73
commit 8f2f4b1bc5
3 changed files with 35 additions and 1 deletions
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25
libraries/AP_HAL_PX4/RCOutput.cpp
View File

@ -18,6 +18,7 @@ using namespace PX4;
void PX4RCOutput::init(void* unused)
{
_perf_rcout = perf_alloc(PC_ELAPSED, "APM_rcout");
_pwm_fd = open(PWM_OUTPUT_DEVICE_PATH, O_RDWR);
if (_pwm_fd == -1) {
hal.scheduler->panic("Unable to open " PWM_OUTPUT_DEVICE_PATH);
@ -67,9 +68,12 @@ void PX4RCOutput::write(uint8_t ch, uint16_t period_us)
if (ch >= PX4_NUM_OUTPUT_CHANNELS) {
return;
}
if (ch > _max_channel) {
_max_channel = ch;
}
if (period_us != _period[ch]) {
ioctl(_pwm_fd, PWM_SERVO_SET(ch), (unsigned long)period_us);
_period[ch] = period_us;
_need_update = true;
}
}
@ -95,4 +99,23 @@ void PX4RCOutput::read(uint16_t* period_us, uint8_t len)
}
}
void PX4RCOutput::_timer_tick(void)
{
uint32_t now = hal.scheduler->micros();
// always send at least at 20Hz, otherwise the IO board may think
// we are dead
if (now - _last_output > 50000) {
_need_update = true;
}
if (_need_update && _pwm_fd != -1) {
_need_update = false;
perf_begin(_perf_rcout);
::write(_pwm_fd, _period, _max_channel*sizeof(_period[0]));
perf_end(_perf_rcout);
_last_output = now;
}
}
#endif // CONFIG_HAL_BOARD

7
libraries/AP_HAL_PX4/RCOutput.h
View File

@ -3,6 +3,7 @@
#define __AP_HAL_PX4_RCOUTPUT_H__
#include <AP_HAL_PX4.h>
#include <systemlib/perf_counter.h>
#define PX4_NUM_OUTPUT_CHANNELS 16
@ -21,10 +22,16 @@ public:
uint16_t read(uint8_t ch);
void read(uint16_t* period_us, uint8_t len);
void _timer_tick(void);
private:
int _pwm_fd;
uint16_t _freq_hz;
uint16_t _period[PX4_NUM_OUTPUT_CHANNELS];
volatile uint8_t _max_channel;
volatile bool _need_update;
perf_counter_t _perf_rcout;
uint32_t _last_output;
};
#endif // __AP_HAL_PX4_RCOUTPUT_H__

4
libraries/AP_HAL_PX4/Scheduler.cpp
View File

@ -18,6 +18,7 @@
#include "UARTDriver.h"
#include "Storage.h"
#include "RCOutput.h"
using namespace PX4;
@ -190,6 +191,9 @@ void *PX4Scheduler::_timer_thread(void)
perf_begin(_perf_timers);
_run_timers(true);
perf_end(_perf_timers);
// process any pending RC output requests
((PX4RCOutput *)hal.rcout)->_timer_tick();
}
return NULL;
}