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pulse clock back to the same speed as the original

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odaki
2020-04-26 09:29:21 +09:00
parent c3f14314fd
commit c4d827c7a8
2 changed files with 15 additions and 16 deletions
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27
Grbl_Esp32/i2s_ioexpander.cpp
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@@ -57,7 +57,7 @@
//
// Configrations for DMA connected I2S
//
// One DMA buffer transfer takes about 1 ms (2000/4 x I2S_IOEXP_USEC_PER_PULSE = 1000 us)
// One DMA buffer transfer takes about 2 ms (2000/4 x I2S_IOEXP_USEC_PER_PULSE = 2000 us)
// If DMA_BUF_COUNT is 5, it will take about 5 ms for all the DMA buffer transfers to finish.
//
// Increasing DMA_BUF_COUNT has the effect of preventing buffer underflow,
@@ -65,7 +65,7 @@
// The number of DMA_BUF_COUNT should be chosen carefully.
//
// Reference information:
// FreeRtoS task time slice = portTICK_PERIOD_MS = 1 ms (ESP32 FreeRtoS port)
// FreeRTOS task time slice = portTICK_PERIOD_MS = 1 ms (ESP32 FreeRTOS port)
//
#define DMA_BUF_COUNT 5 /* number of DMA buffers to store data */
#define DMA_BUF_LEN 2000 /* maximum size in bytes (4092 is DMA's limit) */
@@ -244,8 +244,6 @@ static int i2s_start() {
I2S0.conf.rx_reset = 1;
I2S0.conf.rx_reset = 0;
I2S0.conf1.tx_stop_en = 1; // Prevent unintentional 0's at the start of I2S
I2S0.out_link.addr = (uint32_t)dma.desc[0];
// Connect DMA to FIFO
@@ -255,7 +253,7 @@ static int i2s_start() {
I2S0.out_link.start = 1;
I2S0.conf.tx_start = 1;
I2S0.conf1.tx_stop_en = 0; // BCK, WS start to work
I2S0.conf1.tx_stop_en = 1; // Prevent unintentional 0's at the start of I2S
I2S_EXIT_CRITICAL();
@@ -546,7 +544,7 @@ int i2s_ioexpander_init(i2s_ioexpander_init_t &init_param) {
I2S0.conf.rx_start = 0;
I2S0.conf.tx_msb_right = 1; // Set this bit to place right-channel data at the MSB in the transmit FIFO.
I2S0.conf.tx_right_first = 0; // Set this bit to transmit right-channel data first.
I2S0.conf.tx_right_first = 0; // XXX: Setting this bit allows the right-channel data to be sent first, but on the actual device, 0 is required to send with right-first.
I2S0.conf.tx_slave_mod = 0; // Master
I2S0.fifo_conf.tx_fifo_mod_force_en = 1; //The bit should always be set to 1.
@@ -564,19 +562,20 @@ int i2s_ioexpander_init(i2s_ioexpander_init_t &init_param) {
// i2s_set_clk
//
// set clock (fi2s) 160MHz / 2.5
// set clock (fi2s) 160MHz / 5
I2S0.clkm_conf.clka_en = 0; // Use 160 MHz PLL_D2_CLK as reference
// N + b/a = 2.5
// N = 2
I2S0.clkm_conf.clkm_div_num = 2; // minimum value of 2, reset value of 4, max 256 (I²S clock divider’s integral value)
// b/a = 0.5
I2S0.clkm_conf.clkm_div_b = 1; // 0 at reset
I2S0.clkm_conf.clkm_div_a = 2; // 0 at reset, what about divide by 0? (not an issue)
// N + b/a = 0
// N = 5
I2S0.clkm_conf.clkm_div_num = 5; // minimum value of 2, reset value of 4, max 256 (I²S clock divider’s integral value)
// b/a = 0
I2S0.clkm_conf.clkm_div_b = 0; // 0 at reset
I2S0.clkm_conf.clkm_div_a = 0; // 0 at reset, what about divide by 0? (not an issue)
// Bit clock configuration bit in transmitter mode.
// fbck = fi2s / tx_bck_div_num = (160 MHz / 2.5) / 2 = 32 MHz
// fbck = fi2s / tx_bck_div_num = (160 MHz / 5) / 2 = 16 MHz
I2S0.sample_rate_conf.tx_bck_div_num = 2; // minimum value of 2 defaults to 6
I2S0.sample_rate_conf.rx_bck_div_num = 2;
// Data width is 32-bit. Forgetting this setting will result in a 16-bit transfer.
I2S0.sample_rate_conf.tx_bits_mod = 32;
I2S0.sample_rate_conf.rx_bits_mod = 32;

4
Grbl_Esp32/i2s_ioexpander.h
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@@ -48,8 +48,8 @@
#define I2S_IOEXP_PIN_BASE 128
/* 1000000 usec / ((160000000 Hz) / 2.5 / 2) x 32 bit/pulse x 2(stereo) = 2 usec/pulse */
#define I2S_IOEXP_USEC_PER_PULSE 2
/* 1000000 usec / ((160000000 Hz) / 5 / 2) x 32 bit/pulse x 2(stereo) = 4 usec/pulse */
#define I2S_IOEXP_USEC_PER_PULSE 4
#define IS_I2S_IOEXP_PIN(IO) ((IO) & ~0x7F)
#define I2S_IOEXP_PIN_INDEX(IO) ((IO) & 0x7F)