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Update esp32_i2s_parallel_v2.c

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mrfaptastic 2021-02-19 09:11:55 +00:00
parent 895bb80b43
commit f0999beb51
1 changed files with 20 additions and 9 deletions
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esp32_i2s_parallel_v2.c
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@ -207,22 +207,33 @@ esp_err_t i2s_parallel_driver_install(i2s_port_t port, i2s_parallel_config_t* co
dev->sample_rate_conf.rx_bits_mod = bus_width;
dev->sample_rate_conf.tx_bits_mod = bus_width;
dev->sample_rate_conf.rx_bck_div_num = 1;
dev->sample_rate_conf.tx_bck_div_num = 1;
dev->sample_rate_conf.tx_bck_div_num = 1; // datasheet says this must be 2 or greater (but 1 seems to work)
// note: because it's 1 here, not 2, we need to clkm_div_num = clkm_div_num * 2
// No support for fractional dividers (could probably be ported from official serial i2s driver though)
dev->clkm_conf.val=0; // Clear the clkm_conf struct
dev->clkm_conf.clka_en=0; // Use the 160mhz system clock (PLL_D2_CLK) when '0'
dev->clkm_conf.clkm_div_a=1; // Page 310 of Technical Reference Manual - Clock denominator
dev->clkm_conf.clkm_div_b=1; // Page 310 of Technical Reference Manual - Clock numerator
//
// It's confusing, but the max output the ESP32 can pump out when using I2S *parallel* output is 20Mhz.
// https://easyvolts.com/2018/08/14/esp32-40msps-oscilloscope-project-is-closed-and-here-is-why/
// and https://github.com/espressif/esp-idf/issues/2251
// Igor - "Frequencies above 20MHz do not work in I2S mode."
//printf("esp32_i2s_parallel_2.c > I2S clock divider is %d \n", clk_div_main*2);
// 10Mhz requested will = clk_div_main of 4 for some reason, so *2 = 8, which = 80/8 = 10Mhz gpio output.
dev->clkm_conf.clkm_div_num = clk_div_main*2;
//
// 16bit parallel I2S = calculated clk_div_main (per line ~142) of 4
dev->clkm_conf.val=0; // Clear the clkm_conf struct
dev->clkm_conf.clka_en=0; // Use the 160mhz system clock (PLL_D2_CLK) when '0'
dev->clkm_conf.clkm_div_b=0; // Page 310 of Technical Reference Manual - Clock numerator
dev->clkm_conf.clkm_div_a=0; // Page 310 of Technical Reference Manual - Clock denominator
//
// Final Mhz output =
// Output = 80000000L / tx_bck_div_num / (clkm_div_num + (clkm_div_b/clkm_div_a) )
// Note: clkm_div_num must only be set AFTER clkm_div_b, clkm_div_a, etc. Or weird things happen!
// dev->clkm_conf.clkm_div_num = (clk_div_main*2)+1;
dev->clkm_conf.clkm_div_num=80000000L/(conf->sample_rate + 1);
//printf("esp32_i2s_parallel_2.c > I2S clock divider is %d \n", clk_div_main*2);
// Some fifo conf I don't quite understand
dev->fifo_conf.val = 0;