add neopixel_write implementation, work ok
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hathach
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@ -27,6 +27,238 @@
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#include "py/mphal.h"
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#include "shared-bindings/neopixel_write/__init__.h"
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void common_hal_neopixel_write(const digitalio_digitalinout_obj_t* digitalinout, uint8_t *pixels, uint32_t numBytes) {
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// https://github.com/adafruit/Adafruit_NeoPixel/blob/master/Adafruit_NeoPixel.cpp
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// [[[Begin of the Neopixel NRF52 EasyDMA implementation
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// by the Hackerspace San Salvador]]]
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// This technique uses the PWM peripheral on the NRF52. The PWM uses the
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// EasyDMA feature included on the chip. This technique loads the duty
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// cycle configuration for each cycle when the PWM is enabled. For this
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// to work we need to store a 16 bit configuration for each bit of the
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// RGB(W) values in the pixel buffer.
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// Comparator values for the PWM were hand picked and are guaranteed to
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// be 100% organic to preserve freshness and high accuracy. Current
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// parameters are:
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// * PWM Clock: 16Mhz
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// * Minimum step time: 62.5ns
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// * Time for zero in high (T0H): 0.31ms
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// * Time for one in high (T1H): 0.75ms
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// * Cycle time: 1.25us
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// * Frequency: 800Khz
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// For 400Khz we just double the calculated times.
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// ---------- BEGIN Constants for the EasyDMA implementation -----------
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// The PWM starts the duty cycle in LOW. To start with HIGH we
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// need to set the 15th bit on each register.
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// WS2812 (rev A) timing is 0.35 and 0.7us
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//#define MAGIC_T0H 5UL | (0x8000) // 0.3125us
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//#define MAGIC_T1H 12UL | (0x8000) // 0.75us
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// WS2812B (rev B) timing is 0.4 and 0.8 us
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#define MAGIC_T0H 6UL | (0x8000) // 0.375us
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#define MAGIC_T1H 13UL | (0x8000) // 0.8125us
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#define CTOPVAL 20UL // 1.25us
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// ---------- END Constants for the EasyDMA implementation -------------
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//
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// If there is no device available an alternative cycle-counter
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// implementation is tried.
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// The nRF52832 runs with a fixed clock of 64Mhz. The alternative
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// implementation is the same as the one used for the Teensy 3.0/1/2 but
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// with the Nordic SDK HAL & registers syntax.
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// The number of cycles was hand picked and is guaranteed to be 100%
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// organic to preserve freshness and high accuracy.
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// ---------- BEGIN Constants for cycle counter implementation ---------
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#define CYCLES_800_T0H 18 // ~0.36 uS
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#define CYCLES_800_T1H 41 // ~0.76 uS
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#define CYCLES_800 71 // ~1.25 uS
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// ---------- END of Constants for cycle counter implementation --------
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// find a free PWM device, which is not enabled and has no connected pins
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static NRF_PWM_Type* find_free_pwm (void) {
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NRF_PWM_Type* PWM[3] = { NRF_PWM0, NRF_PWM1, NRF_PWM2 };
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for ( int device = 0; device < 3; device++ ) {
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if ( (PWM[device]->ENABLE == 0) && (PWM[device]->PSEL.OUT[0] & PWM_PSEL_OUT_CONNECT_Msk)
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&& (PWM[device]->PSEL.OUT[1] & PWM_PSEL_OUT_CONNECT_Msk)
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&& (PWM[device]->PSEL.OUT[2] & PWM_PSEL_OUT_CONNECT_Msk)
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&& (PWM[device]->PSEL.OUT[3] & PWM_PSEL_OUT_CONNECT_Msk) ) {
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return PWM[device];
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}
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}
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return NULL;
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}
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void common_hal_neopixel_write (const digitalio_digitalinout_obj_t* digitalinout, uint8_t *pixels, uint32_t numBytes) {
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// To support both the SoftDevice + Neopixels we use the EasyDMA
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// feature from the NRF25. However this technique implies to
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// generate a pattern and store it on the memory. The actual
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// memory used in bytes corresponds to the following formula:
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// totalMem = numBytes*8*2+(2*2)
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// The two additional bytes at the end are needed to reset the
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// sequence.
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//
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// If there is not enough memory, we will fall back to cycle counter
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// using DWT
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uint32_t pattern_size = numBytes * 8 * sizeof(uint16_t) + 2 * sizeof(uint16_t);
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uint16_t* pixels_pattern = NULL;
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NRF_PWM_Type* pwm = find_free_pwm();
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// only malloc if there is PWM device available
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if ( pwm != NULL ) {
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pixels_pattern = (uint16_t *) m_malloc(pattern_size, false);
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}
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// Use the identified device to choose the implementation
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// If a PWM device is available use DMA
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if ( (pixels_pattern != NULL) && (pwm != NULL) ) {
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uint16_t pos = 0; // bit position
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for ( uint16_t n = 0; n < numBytes; n++ ) {
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uint8_t pix = pixels[n];
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for ( uint8_t mask = 0x80, i = 0; mask > 0; mask >>= 1, i++ ) {
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pixels_pattern[pos] = (pix & mask) ? MAGIC_T1H : MAGIC_T0H;
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pos++;
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}
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}
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// Zero padding to indicate the end of sequence
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pixels_pattern[++pos] = 0 | (0x8000); // Seq end
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pixels_pattern[++pos] = 0 | (0x8000); // Seq end
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// Set the wave mode to count UP
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pwm->MODE = (PWM_MODE_UPDOWN_Up << PWM_MODE_UPDOWN_Pos);
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// Set the PWM to use the 16MHz clock
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pwm->PRESCALER = (PWM_PRESCALER_PRESCALER_DIV_1 << PWM_PRESCALER_PRESCALER_Pos);
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// Setting of the maximum count
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// but keeping it on 16Mhz allows for more granularity just
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// in case someone wants to do more fine-tuning of the timing.
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pwm->COUNTERTOP = (CTOPVAL << PWM_COUNTERTOP_COUNTERTOP_Pos);
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// Disable loops, we want the sequence to repeat only once
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pwm->LOOP = (PWM_LOOP_CNT_Disabled << PWM_LOOP_CNT_Pos);
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// On the "Common" setting the PWM uses the same pattern for the
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// for supported sequences. The pattern is stored on half-word
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// of 16bits
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pwm->DECODER = (PWM_DECODER_LOAD_Common << PWM_DECODER_LOAD_Pos)
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| (PWM_DECODER_MODE_RefreshCount << PWM_DECODER_MODE_Pos);
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// Pointer to the memory storing the patter
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pwm->SEQ[0].PTR = (uint32_t) (pixels_pattern) << PWM_SEQ_PTR_PTR_Pos;
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// Calculation of the number of steps loaded from memory.
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pwm->SEQ[0].CNT = (pattern_size / sizeof(uint16_t)) << PWM_SEQ_CNT_CNT_Pos;
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// The following settings are ignored with the current config.
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pwm->SEQ[0].REFRESH = 0;
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pwm->SEQ[0].ENDDELAY = 0;
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// The Neopixel implementation is a blocking algorithm. DMA
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// allows for non-blocking operation. To "simulate" a blocking
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// operation we enable the interruption for the end of sequence
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// and block the execution thread until the event flag is set by
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// the peripheral.
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// pwm->INTEN |= (PWM_INTEN_SEQEND0_Enabled<<PWM_INTEN_SEQEND0_Pos);
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// PSEL must be configured before enabling PWM
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pwm->PSEL.OUT[0] = ( digitalinout->pin->port*32 + digitalinout->pin->pin );
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// Enable the PWM
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pwm->ENABLE = 1;
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// After all of this and many hours of reading the documentation
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// we are ready to start the sequence...
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pwm->EVENTS_SEQEND[0] = 0;
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pwm->TASKS_SEQSTART[0] = 1;
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// But we have to wait for the flag to be set.
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while ( !pwm->EVENTS_SEQEND[0] ) {
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//#ifdef MICROPY_VM_HOOK_LOOP
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// MICROPY_VM_HOOK_LOOP
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//#endif
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}
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// Before leave we clear the flag for the event.
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pwm->EVENTS_SEQEND[0] = 0;
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// We need to disable the device and disconnect
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// all the outputs before leave or the device will not
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// be selected on the next call.
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// TODO: Check if disabling the device causes performance issues.
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pwm->ENABLE = 0;
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pwm->PSEL.OUT[0] = 0xFFFFFFFFUL;
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m_free(pixels_pattern);
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} // End of DMA implementation
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// ---------------------------------------------------------------------
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else {
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// Fall back to DWT
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// If you are using the Bluetooth SoftDevice we advise you to not disable
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// the interrupts. Disabling the interrupts even for short periods of time
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// causes the SoftDevice to stop working.
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// Disable the interrupts only in cases where you need high performance for
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// the LEDs and if you are not using the EasyDMA feature.
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__disable_irq();
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NRF_GPIO_Type* port = ( digitalinout->pin->port ? NRF_P1 : NRF_P0 );
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uint32_t pinMask = ( 1UL << digitalinout->pin->pin );
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uint32_t CYCLES_X00 = CYCLES_800;
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uint32_t CYCLES_X00_T1H = CYCLES_800_T1H;
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uint32_t CYCLES_X00_T0H = CYCLES_800_T0H;
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// Enable DWT in debug core
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CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
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DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
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// Tries to re-send the frame if is interrupted by the SoftDevice.
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while ( 1 ) {
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uint8_t *p = pixels;
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uint32_t cycStart = DWT->CYCCNT;
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uint32_t cyc = 0;
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for ( uint16_t n = 0; n < numBytes; n++ ) {
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uint8_t pix = *p++;
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for ( uint8_t mask = 0x80; mask; mask >>= 1 ) {
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while ( DWT->CYCCNT - cyc < CYCLES_X00 )
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;
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cyc = DWT->CYCCNT;
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port->OUTSET |= pinMask;
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if ( pix & mask ) {
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while ( DWT->CYCCNT - cyc < CYCLES_X00_T1H )
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;
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} else {
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while ( DWT->CYCCNT - cyc < CYCLES_X00_T0H )
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;
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}
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port->OUTCLR |= pinMask;
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}
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}
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while ( DWT->CYCCNT - cyc < CYCLES_X00 )
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;
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// If total time longer than 25%, resend the whole data.
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// Since we are likely to be interrupted by SoftDevice
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if ( (DWT->CYCCNT - cycStart) < (8 * numBytes * ((CYCLES_X00 * 5) / 4)) ) {
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break;
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}
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// re-send need 300us delay
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mp_hal_delay_us(300);
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}
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// Enable interrupts again
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__enable_irq();
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}
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}
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