Hi friend,
We have a project with BLE connection. It sends out the Manchester data and the data modulates with 125KHz. Can we use PWM to do that? Will the data format be disturbed by BLE? Can I increase the priority to avoid the data format being disturbed? Could anyone guide how to do that? The long cycle is 114 uS and the short cycle is 52 uS.
Best wishes
Ted Wu
Hi Sigurd,
I have an array data. I separate them to many 80-byte block's data. The data of 80 bytes need to be encoded to Manchester data and it is modulated with 125KHz. I change your example to send out a bit data. It occupies 80*8*26*2 word memory space if I want to send 80 bytes data. It occupies too many memory. Do you have another idea to save memory? The green block on attached file is 125KHz modulation.
Best wishes
Ted Wu
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/** @file
* @defgroup pwm_example_main main.c
* @{
* @ingroup pwm_example
*
* @brief PWM Example Application main file.
*
* This file contains the source code for a sample application using PWM.
*/
#include <stdio.h>
#include <string.h>
#include "nrf_drv_pwm.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "boards.h"
#include "bsp.h"
#include "app_timer.h"
#include "nrf_drv_clock.h"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
static nrf_drv_pwm_t m_pwm0 = NRF_DRV_PWM_INSTANCE(0);
#define PWM_PIN 3
#define HIGH 0x00
#define LOW 0x8000
// 1 cycle ~ 4μs
#define HIGH_52us HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH
#define LOW_52us LOW,LOW,LOW,LOW,LOW,LOW,LOW,LOW,LOW,LOW,LOW,LOW,LOW
#define HIGH_114us HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH, \
HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH,HIGH, \
HIGH,HIGH
#define LOGIC_1 HIGH,LOW, HIGH,LOW, HIGH,LOW, HIGH,LOW, HIGH,LOW, HIGH,LOW, HIGH, \
LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW
#define LOGIC_0 LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW, LOW, HIGH, \
LOW, HIGH,LOW, HIGH,LOW, HIGH,LOW, HIGH,LOW, HIGH,LOW, HIGH,LOW
static void pwm_init(void)
{
nrf_drv_pwm_config_t config =
{
// These are the common configuration options we use for all PWM
// instances.
.irq_priority = APP_IRQ_PRIORITY_LOWEST,
.count_mode = NRF_PWM_MODE_UP,
.step_mode = NRF_PWM_STEP_AUTO,
};
config.base_clock = NRF_PWM_CLK_16MHz;
config.top_value = 64;
config.load_mode = NRF_PWM_LOAD_COMMON;
config.output_pins[0] = PWM_PIN | NRF_DRV_PWM_PIN_INVERTED;
config.output_pins[1] = NRF_DRV_PWM_PIN_NOT_USED;
config.output_pins[2] = NRF_DRV_PWM_PIN_NOT_USED;
config.output_pins[3] = NRF_DRV_PWM_PIN_NOT_USED;
APP_ERROR_CHECK(nrf_drv_pwm_init(&m_pwm0, &config, NULL));
}
static void start_pwm_demo()
{
// Sequence 0:
static nrf_pwm_values_common_t seq0_values[] =
{
// HIGH_114us,LOW_52us
LOGIC_1,LOGIC_0
};
nrf_pwm_sequence_t const pwm0_seq0 =
{
.values.p_common = seq0_values,
.length = NRF_PWM_VALUES_LENGTH(seq0_values),
.repeats = 0,
.end_delay = 0
};
(void)nrf_drv_pwm_simple_playback(&m_pwm0, &pwm0_seq0, 1,
NRF_DRV_PWM_FLAG_LOOP);
// // Sequence 1 :
// static nrf_pwm_values_common_t seq1_values[2] = {0,0};
//
// nrf_pwm_sequence_t const pwm0_seq1 =
// {
// .values.p_common = seq1_values,
// .length = NRF_PWM_VALUES_LENGTH(seq1_values),
// .repeats = 0,
// .end_delay = 0
// };
// (void)nrf_drv_pwm_complex_playback(&m_pwm0, &pwm0_seq0, &pwm0_seq1, 1,
// NRF_DRV_PWM_FLAG_LOOP);
}
static void bsp_evt_handler(bsp_event_t evt)
{
switch (evt)
{
// Button 1 on DK - start pwm demo
case BSP_EVENT_KEY_0:
//start_pwm_demo();
break;
default:
return;
}
}
void app_error_fault_handler(uint32_t id, uint32_t pc, uint32_t info)
{
bsp_board_leds_on();
app_error_save_and_stop(id, pc, info);
}
static void init_bsp()
{
APP_ERROR_CHECK(nrf_drv_clock_init());
nrf_drv_clock_lfclk_request(NULL);
APP_ERROR_CHECK(app_timer_init());
APP_ERROR_CHECK(bsp_init(BSP_INIT_BUTTONS, bsp_evt_handler));
APP_ERROR_CHECK(bsp_buttons_enable());
}
int main(void)
{
APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
NRF_LOG_DEFAULT_BACKENDS_INIT();
NRF_LOG_INFO("PWM example started.");
init_bsp();
bool accurate_HFCLK = true;
if(accurate_HFCLK)
{
// Start accurate HFCLK (XOSC)
NRF_CLOCK->TASKS_HFCLKSTART = 1;
while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) ;
NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
}
pwm_init();
start_pwm_demo();
for (;;)
{
// Wait for an event.
__WFE();
// Clear the event register.
__SEV();
__WFE();
NRF_LOG_FLUSH();
}
}
/** @} */