From 1678f417445703750e187b1b8a83c8c3e0e3796f Mon Sep 17 00:00:00 2001 From: Jon Rob Date: Mon, 8 Jun 2020 06:29:43 +0000 Subject: [PATCH] esp32/esp32_rmt: Extend RMT to support carrier feature. The ESP32 RMT peripheral has hardware support for a carrier frequency, and this commit exposes it to Python with the keyword arguments carrier_freq and carrier_duty_percent in the constructor. Example usage: r = esp32.RMT(0, pin=Pin(2), clock_div=80, carrier_freq=38000, carrier_duty_percent=50) --- docs/library/esp32.rst | 17 ++++++++++++++--- ports/esp32/esp32_rmt.c | 30 ++++++++++++++++++++++++++---- 2 files changed, 40 insertions(+), 7 deletions(-) diff --git a/docs/library/esp32.rst b/docs/library/esp32.rst index 33b779a214..715afdddeb 100644 --- a/docs/library/esp32.rst +++ b/docs/library/esp32.rst @@ -151,6 +151,11 @@ used to transmit or receive many other types of digital signals:: r = esp32.RMT(0, pin=Pin(18), clock_div=8) r # RMT(channel=0, pin=18, source_freq=80000000, clock_div=8) + + # To use carrier frequency + r = esp32.RMT(0, pin=Pin(18), clock_div=8, carrier_freq=38000) + r # RMT(channel=0, pin=18, source_freq=80000000, clock_div=8, carrier_freq=38000, carrier_duty_percent=50) + # The channel resolution is 100ns (1/(source_freq/clock_div)). r.write_pulses((1, 20, 2, 40), start=0) # Send 0 for 100ns, 1 for 2000ns, 0 for 200ns, 1 for 4000ns @@ -164,6 +169,9 @@ define the pulses. multiplying the resolution by a 15-bit (0-32,768) number. There are eight channels (0-7) and each can have a different clock divider. +To enable the carrier frequency feature of the esp32 hardware, specify the +``carrier_freq`` as something like 38000, a typical IR carrier frequency. + So, in the example above, the 80MHz clock is divided by 8. Thus the resolution is (1/(80Mhz/8)) 100ns. Since the ``start`` level is 0 and toggles with each number, the bitstream is ``0101`` with durations of [100ns, 2000ns, @@ -174,17 +182,20 @@ For more details see Espressif's `ESP-IDF RMT documentation. .. Warning:: The current MicroPython RMT implementation lacks some features, most notably - receiving pulses and carrier transmit. RMT should be considered a + receiving pulses. RMT should be considered a *beta feature* and the interface may change in the future. -.. class:: RMT(channel, \*, pin=None, clock_div=8) +.. class:: RMT(channel, \*, pin=None, clock_div=8, carrier_freq=0, carrier_duty_percent=50) This class provides access to one of the eight RMT channels. *channel* is required and identifies which RMT channel (0-7) will be configured. *pin*, also required, configures which Pin is bound to the RMT channel. *clock_div* is an 8-bit clock divider that divides the source clock (80MHz) to the RMT - channel allowing the resolution to be specified. + channel allowing the resolution to be specified. *carrier_freq* is used to + enable the carrier feature and specify its frequency, default value is ``0`` + (not enabled). To enable, specify a positive integer. *carrier_duty_percent* + defaults to 50. .. method:: RMT.source_freq() diff --git a/ports/esp32/esp32_rmt.c b/ports/esp32/esp32_rmt.c index 25b7b38089..846c80d478 100644 --- a/ports/esp32/esp32_rmt.c +++ b/ports/esp32/esp32_rmt.c @@ -52,6 +52,8 @@ typedef struct _esp32_rmt_obj_t { uint8_t channel_id; gpio_num_t pin; uint8_t clock_div; + uint16_t carrier_duty_percent; + uint32_t carrier_freq; mp_uint_t num_items; rmt_item32_t *items; } esp32_rmt_obj_t; @@ -61,6 +63,8 @@ STATIC mp_obj_t esp32_rmt_make_new(const mp_obj_type_t *type, size_t n_args, siz { MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = -1} }, { MP_QSTR_pin, MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} }, { MP_QSTR_clock_div, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 8} }, // 100ns resolution + { MP_QSTR_carrier_duty_percent, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 50} }, + { MP_QSTR_carrier_freq, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} }, }; mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)]; mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args); @@ -68,6 +72,16 @@ STATIC mp_obj_t esp32_rmt_make_new(const mp_obj_type_t *type, size_t n_args, siz gpio_num_t pin_id = machine_pin_get_id(args[1].u_obj); mp_uint_t clock_div = args[2].u_int; + bool carrier_en = false; + mp_uint_t carrier_duty_percent = 0; + mp_uint_t carrier_freq = 0; + + if (args[4].u_int > 0) { + carrier_en = true; + carrier_duty_percent = args[3].u_int; + carrier_freq = args[4].u_int; + } + if (clock_div < 1 || clock_div > 255) { mp_raise_ValueError(MP_ERROR_TEXT("clock_div must be between 1 and 255")); } @@ -77,6 +91,8 @@ STATIC mp_obj_t esp32_rmt_make_new(const mp_obj_type_t *type, size_t n_args, siz self->channel_id = channel_id; self->pin = pin_id; self->clock_div = clock_div; + self->carrier_duty_percent = carrier_duty_percent; + self->carrier_freq = carrier_freq; rmt_config_t config; config.rmt_mode = RMT_MODE_TX; @@ -85,11 +101,11 @@ STATIC mp_obj_t esp32_rmt_make_new(const mp_obj_type_t *type, size_t n_args, siz config.mem_block_num = 1; config.tx_config.loop_en = 0; - config.tx_config.carrier_en = 0; + config.tx_config.carrier_en = carrier_en; config.tx_config.idle_output_en = 1; config.tx_config.idle_level = 0; - config.tx_config.carrier_duty_percent = 0; - config.tx_config.carrier_freq_hz = 0; + config.tx_config.carrier_duty_percent = self->carrier_duty_percent; + config.tx_config.carrier_freq_hz = self->carrier_freq; config.tx_config.carrier_level = 1; config.clk_div = self->clock_div; @@ -103,8 +119,14 @@ STATIC mp_obj_t esp32_rmt_make_new(const mp_obj_type_t *type, size_t n_args, siz STATIC void esp32_rmt_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) { esp32_rmt_obj_t *self = MP_OBJ_TO_PTR(self_in); if (self->pin != -1) { - mp_printf(print, "RMT(channel=%u, pin=%u, source_freq=%u, clock_div=%u)", + mp_printf(print, "RMT(channel=%u, pin=%u, source_freq=%u, clock_div=%u", self->channel_id, self->pin, APB_CLK_FREQ, self->clock_div); + if (self->carrier_freq > 0) { + mp_printf(print, ", carrier_freq=%u, carrier_duty_percent=%u)", + self->carrier_freq, self->carrier_duty_percent); + } else { + mp_printf(print, ")"); + } } else { mp_printf(print, "RMT()"); }