ports/esp32/machine_hw_spi.c - lite/micropython - Linaro Git Browser

 /*
  * This file is part of the MicroPython project, http://micropython.org/
  *
  * The MIT License (MIT)
  *
  * Copyright (c) 2017 "Eric Poulsen" <eric@zyxod.com>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */

 #include <stdio.h>
 #include <stdint.h>
 #include <string.h>

 #include "py/runtime.h"
 #include "py/stream.h"
 #include "py/mphal.h"
 #include "extmod/machine_spi.h"
 #include "modmachine.h"

 #include "driver/spi_master.h"

 #define MP_HW_SPI_MAX_XFER_BYTES (4092)
 #define MP_HW_SPI_MAX_XFER_BITS (MP_HW_SPI_MAX_XFER_BYTES * 8) // Has to be an even multiple of 8

 typedef struct _machine_hw_spi_obj_t {
     mp_obj_base_t base;
     spi_host_device_t host;
     uint32_t baudrate;
     uint8_t polarity;
     uint8_t phase;
     uint8_t bits;
     uint8_t firstbit;
     int8_t sck;
     int8_t mosi;
     int8_t miso;
     spi_device_handle_t spi;
     enum {
         MACHINE_HW_SPI_STATE_NONE,
         MACHINE_HW_SPI_STATE_INIT,
         MACHINE_HW_SPI_STATE_DEINIT
     } state;
 } machine_hw_spi_obj_t;

 STATIC void machine_hw_spi_deinit_internal(machine_hw_spi_obj_t *self) {
     switch (spi_bus_remove_device(self->spi)) {
         case ESP_ERR_INVALID_ARG:
             mp_raise_msg(&mp_type_OSError, "invalid configuration");
             return;

         case ESP_ERR_INVALID_STATE:
             mp_raise_msg(&mp_type_OSError, "SPI device already freed");
             return;
     }

     switch (spi_bus_free(self->host)) {
         case ESP_ERR_INVALID_ARG:
             mp_raise_msg(&mp_type_OSError, "invalid configuration");
             return;

         case ESP_ERR_INVALID_STATE:
             mp_raise_msg(&mp_type_OSError, "SPI bus already freed");
             return;
     }

     int8_t pins[3] = {self->miso, self->mosi, self->sck};

     for (int i = 0; i < 3; i++) {
         if (pins[i] != -1) {
             gpio_pad_select_gpio(pins[i]);
             gpio_matrix_out(pins[i], SIG_GPIO_OUT_IDX, false, false);
             gpio_set_direction(pins[i], GPIO_MODE_INPUT);
         }
     }
 }

 STATIC void machine_hw_spi_init_internal(
     machine_hw_spi_obj_t    *self,
     int8_t                  host,
     int32_t                 baudrate,
     int8_t                  polarity,
     int8_t                  phase,
     int8_t                  bits,
     int8_t                  firstbit,
     int8_t                  sck,
     int8_t                  mosi,
     int8_t                  miso) {

     // if we're not initialized, then we're
     // implicitly 'changed', since this is the init routine
     bool changed = self->state != MACHINE_HW_SPI_STATE_INIT;

     esp_err_t ret;

     machine_hw_spi_obj_t old_self = *self;

     if (host != -1 && host != self->host) {
         self->host = host;
         changed = true;
     }

     if (baudrate != -1 && baudrate != self->baudrate) {
         self->baudrate = baudrate;
         changed = true;
     }

     if (polarity != -1 && polarity != self->polarity) {
         self->polarity = polarity;
         changed = true;
     }

     if (phase != -1 && phase != self->phase) {
         self->phase =  phase;
         changed = true;
     }

     if (bits != -1 && bits != self->bits) {
         self->bits = bits;
         changed = true;
     }

     if (firstbit != -1 && firstbit != self->firstbit) {
         self->firstbit = firstbit;
         changed = true;
     }

     if (sck != -2 && sck != self->sck) {
         self->sck = sck;
         changed = true;
     }

     if (mosi != -2 && mosi != self->mosi) {
         self->mosi = mosi;
         changed = true;
     }

     if (miso != -2 && miso != self->miso) {
         self->miso = miso;
         changed = true;
     }

     if (self->host != HSPI_HOST && self->host != VSPI_HOST) {
         mp_raise_ValueError("SPI ID must be either HSPI(1) or VSPI(2)");
     }

     if (changed) {
         if (self->state == MACHINE_HW_SPI_STATE_INIT) {
             self->state = MACHINE_HW_SPI_STATE_DEINIT;
             machine_hw_spi_deinit_internal(&old_self);
         }
     } else {
         return; // no changes
     }

     spi_bus_config_t buscfg = {
         .miso_io_num = self->miso,
         .mosi_io_num = self->mosi,
         .sclk_io_num = self->sck,
         .quadwp_io_num = -1,
         .quadhd_io_num = -1
     };

     spi_device_interface_config_t devcfg = {
         .clock_speed_hz = self->baudrate,
         .mode = self->phase | (self->polarity << 1),
         .spics_io_num = -1, // No CS pin
         .queue_size = 1,
         .flags = self->firstbit == MICROPY_PY_MACHINE_SPI_LSB ? SPI_DEVICE_TXBIT_LSBFIRST | SPI_DEVICE_RXBIT_LSBFIRST : 0,
         .pre_cb = NULL
     };

     //Initialize the SPI bus

     // Select DMA channel based on the hardware SPI host
     int dma_chan = 0;
     if (self->host == HSPI_HOST) {
         dma_chan = 1;
     } else if (self->host == VSPI_HOST) {
         dma_chan = 2;
     }

     ret = spi_bus_initialize(self->host, &buscfg, dma_chan);
     switch (ret) {
         case ESP_ERR_INVALID_ARG:
             mp_raise_msg(&mp_type_OSError, "invalid configuration");
             return;

         case ESP_ERR_INVALID_STATE:
             mp_raise_msg(&mp_type_OSError, "SPI device already in use");
             return;
     }

     ret = spi_bus_add_device(self->host, &devcfg, &self->spi);
     switch (ret) {
         case ESP_ERR_INVALID_ARG:
             mp_raise_msg(&mp_type_OSError, "invalid configuration");
             spi_bus_free(self->host);
             return;

         case ESP_ERR_NO_MEM:
             mp_raise_msg(&mp_type_OSError, "out of memory");
             spi_bus_free(self->host);
             return;

         case ESP_ERR_NOT_FOUND:
             mp_raise_msg(&mp_type_OSError, "no free slots");
             spi_bus_free(self->host);
             return;
     }
     self->state = MACHINE_HW_SPI_STATE_INIT;
 }

 STATIC void machine_hw_spi_deinit(mp_obj_base_t *self_in) {
     machine_hw_spi_obj_t *self = (machine_hw_spi_obj_t *) self_in;
     if (self->state == MACHINE_HW_SPI_STATE_INIT) {
         self->state = MACHINE_HW_SPI_STATE_DEINIT;
         machine_hw_spi_deinit_internal(self);
     }
 }

 STATIC void machine_hw_spi_transfer(mp_obj_base_t *self_in, size_t len, const uint8_t *src, uint8_t *dest) {
     machine_hw_spi_obj_t *self = MP_OBJ_TO_PTR(self_in);

     if (self->state == MACHINE_HW_SPI_STATE_DEINIT) {
         mp_raise_msg(&mp_type_OSError, "transfer on deinitialized SPI");
         return;
     }

     struct spi_transaction_t transaction = { 0 };

     // Round to nearest whole set of bits
     int bits_to_send = len * 8 / self->bits * self->bits;


     if (len <= 4) {
         if (src != NULL) {
             memcpy(&transaction.tx_data, src, len);
         }

         transaction.flags = SPI_TRANS_USE_TXDATA | SPI_TRANS_USE_RXDATA;
         transaction.length = bits_to_send;
         spi_device_transmit(self->spi, &transaction);

         if (dest != NULL) {
             memcpy(dest, &transaction.rx_data, len);
         }
     } else {
         int offset = 0;
         int bits_remaining = bits_to_send;

         while (bits_remaining) {
             memset(&transaction, 0, sizeof(transaction));

             transaction.length =
                 bits_remaining > MP_HW_SPI_MAX_XFER_BITS ? MP_HW_SPI_MAX_XFER_BITS : bits_remaining;

             if (src != NULL) {
                 transaction.tx_buffer = src + offset;
             }
             if (dest != NULL) {
                 transaction.rx_buffer = dest + offset;
             }

             spi_device_transmit(self->spi, &transaction);
             bits_remaining -= transaction.length;

             // doesn't need ceil(); loop ends when bits_remaining is 0
             offset += transaction.length / 8;
         }
     }
 }

 /******************************************************************************/
 // MicroPython bindings for hw_spi

 STATIC void machine_hw_spi_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
     machine_hw_spi_obj_t *self = MP_OBJ_TO_PTR(self_in);
     mp_printf(print, "SPI(id=%u, baudrate=%u, polarity=%u, phase=%u, bits=%u, firstbit=%u, sck=%d, mosi=%d, miso=%d)",
               self->host, self->baudrate, self->polarity,
               self->phase, self->bits, self->firstbit,
               self->sck, self->mosi, self->miso);
 }

 STATIC void machine_hw_spi_init(mp_obj_base_t *self_in, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     machine_hw_spi_obj_t *self = (machine_hw_spi_obj_t *) self_in;

     enum { ARG_id, ARG_baudrate, ARG_polarity, ARG_phase, ARG_bits, ARG_firstbit, ARG_sck, ARG_mosi, ARG_miso };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_id,       MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_phase,    MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_bits,     MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_firstbit, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_sck,      MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_mosi,     MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_miso,     MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
     };

     mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args),
                      allowed_args, args);
     int8_t sck, mosi, miso;

     if (args[ARG_sck].u_obj == MP_OBJ_NULL) {
         sck = -2;
     } else if (args[ARG_sck].u_obj == mp_const_none) {
         sck = -1;
     } else {
         sck = machine_pin_get_id(args[ARG_sck].u_obj);
     }

     if (args[ARG_miso].u_obj == MP_OBJ_NULL) {
         miso = -2;
     } else if (args[ARG_miso].u_obj == mp_const_none) {
         miso = -1;
     } else {
         miso = machine_pin_get_id(args[ARG_miso].u_obj);
     }

     if (args[ARG_mosi].u_obj == MP_OBJ_NULL) {
         mosi = -2;
     } else if (args[ARG_mosi].u_obj == mp_const_none) {
         mosi = -1;
     } else {
         mosi = machine_pin_get_id(args[ARG_mosi].u_obj);
     }

     machine_hw_spi_init_internal(self, args[ARG_id].u_int, args[ARG_baudrate].u_int,
                                  args[ARG_polarity].u_int, args[ARG_phase].u_int, args[ARG_bits].u_int,
                                  args[ARG_firstbit].u_int, sck, mosi, miso);
 }

 mp_obj_t machine_hw_spi_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
     enum { ARG_id, ARG_baudrate, ARG_polarity, ARG_phase, ARG_bits, ARG_firstbit, ARG_sck, ARG_mosi, ARG_miso };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_id,       MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = -1} },
         { MP_QSTR_baudrate, MP_ARG_INT, {.u_int = 500000} },
         { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
         { MP_QSTR_phase,    MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
         { MP_QSTR_bits,     MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 8} },
         { MP_QSTR_firstbit, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = MICROPY_PY_MACHINE_SPI_MSB} },
         { MP_QSTR_sck,      MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_mosi,     MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
         { MP_QSTR_miso,     MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
     };
     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);

     machine_hw_spi_obj_t *self = m_new_obj(machine_hw_spi_obj_t);
     self->base.type = &machine_hw_spi_type;

     machine_hw_spi_init_internal(
         self,
         args[ARG_id].u_int,
         args[ARG_baudrate].u_int,
         args[ARG_polarity].u_int,
         args[ARG_phase].u_int,
         args[ARG_bits].u_int,
         args[ARG_firstbit].u_int,
         args[ARG_sck].u_obj == MP_OBJ_NULL ? -1 : machine_pin_get_id(args[ARG_sck].u_obj),
         args[ARG_mosi].u_obj == MP_OBJ_NULL ? -1 : machine_pin_get_id(args[ARG_mosi].u_obj),
         args[ARG_miso].u_obj == MP_OBJ_NULL ? -1 : machine_pin_get_id(args[ARG_miso].u_obj));

     return MP_OBJ_FROM_PTR(self);
 }

 STATIC const mp_machine_spi_p_t machine_hw_spi_p = {
     .init = machine_hw_spi_init,
     .deinit = machine_hw_spi_deinit,
     .transfer = machine_hw_spi_transfer,
 };

 const mp_obj_type_t machine_hw_spi_type = {
     { &mp_type_type },
     .name = MP_QSTR_SPI,
     .print = machine_hw_spi_print,
     .make_new = machine_hw_spi_make_new,
     .protocol = &machine_hw_spi_p,
     .locals_dict = (mp_obj_dict_t *) &mp_machine_spi_locals_dict,
 };
	/*
	* This file is part of the MicroPython project, http://micropython.org/
	*
	* The MIT License (MIT)
	*
	* Copyright (c) 2017 "Eric Poulsen" <eric@zyxod.com>
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/

	#include <stdio.h>
	#include <stdint.h>
	#include <string.h>

	#include "py/runtime.h"
	#include "py/stream.h"
	#include "py/mphal.h"
	#include "extmod/machine_spi.h"
	#include "modmachine.h"

	#include "driver/spi_master.h"

	#define MP_HW_SPI_MAX_XFER_BYTES (4092)
	#define MP_HW_SPI_MAX_XFER_BITS (MP_HW_SPI_MAX_XFER_BYTES * 8) // Has to be an even multiple of 8

	typedef struct _machine_hw_spi_obj_t {
	mp_obj_base_t base;
	spi_host_device_t host;
	uint32_t baudrate;
	uint8_t polarity;
	uint8_t phase;
	uint8_t bits;
	uint8_t firstbit;
	int8_t sck;
	int8_t mosi;
	int8_t miso;
	spi_device_handle_t spi;
	enum {
	MACHINE_HW_SPI_STATE_NONE,
	MACHINE_HW_SPI_STATE_INIT,
	MACHINE_HW_SPI_STATE_DEINIT
	} state;
	} machine_hw_spi_obj_t;

	STATIC void machine_hw_spi_deinit_internal(machine_hw_spi_obj_t *self) {
	switch (spi_bus_remove_device(self->spi)) {
	case ESP_ERR_INVALID_ARG:
	mp_raise_msg(&mp_type_OSError, "invalid configuration");
	return;

	case ESP_ERR_INVALID_STATE:
	mp_raise_msg(&mp_type_OSError, "SPI device already freed");
	return;
	}

	switch (spi_bus_free(self->host)) {
	case ESP_ERR_INVALID_ARG:
	mp_raise_msg(&mp_type_OSError, "invalid configuration");
	return;

	case ESP_ERR_INVALID_STATE:
	mp_raise_msg(&mp_type_OSError, "SPI bus already freed");
	return;
	}

	int8_t pins[3] = {self->miso, self->mosi, self->sck};

	for (int i = 0; i < 3; i++) {
	if (pins[i] != -1) {
	gpio_pad_select_gpio(pins[i]);
	gpio_matrix_out(pins[i], SIG_GPIO_OUT_IDX, false, false);
	gpio_set_direction(pins[i], GPIO_MODE_INPUT);
	}
	}
	}

	STATIC void machine_hw_spi_init_internal(
	machine_hw_spi_obj_t *self,
	int8_t host,
	int32_t baudrate,
	int8_t polarity,
	int8_t phase,
	int8_t bits,
	int8_t firstbit,
	int8_t sck,
	int8_t mosi,
	int8_t miso) {

	// if we're not initialized, then we're
	// implicitly 'changed', since this is the init routine
	bool changed = self->state != MACHINE_HW_SPI_STATE_INIT;

	esp_err_t ret;

	machine_hw_spi_obj_t old_self = *self;

	if (host != -1 && host != self->host) {
	self->host = host;
	changed = true;
	}

	if (baudrate != -1 && baudrate != self->baudrate) {
	self->baudrate = baudrate;
	changed = true;
	}

	if (polarity != -1 && polarity != self->polarity) {
	self->polarity = polarity;
	changed = true;
	}

	if (phase != -1 && phase != self->phase) {
	self->phase = phase;
	changed = true;
	}

	if (bits != -1 && bits != self->bits) {
	self->bits = bits;
	changed = true;
	}

	if (firstbit != -1 && firstbit != self->firstbit) {
	self->firstbit = firstbit;
	changed = true;
	}

	if (sck != -2 && sck != self->sck) {
	self->sck = sck;
	changed = true;
	}

	if (mosi != -2 && mosi != self->mosi) {
	self->mosi = mosi;
	changed = true;
	}

	if (miso != -2 && miso != self->miso) {
	self->miso = miso;
	changed = true;
	}

	if (self->host != HSPI_HOST && self->host != VSPI_HOST) {
	mp_raise_ValueError("SPI ID must be either HSPI(1) or VSPI(2)");
	}

	if (changed) {
	if (self->state == MACHINE_HW_SPI_STATE_INIT) {
	self->state = MACHINE_HW_SPI_STATE_DEINIT;
	machine_hw_spi_deinit_internal(&old_self);
	}
	} else {
	return; // no changes
	}

	spi_bus_config_t buscfg = {
	.miso_io_num = self->miso,
	.mosi_io_num = self->mosi,
	.sclk_io_num = self->sck,
	.quadwp_io_num = -1,
	.quadhd_io_num = -1
	};

	spi_device_interface_config_t devcfg = {
	.clock_speed_hz = self->baudrate,
	.mode = self->phase \| (self->polarity << 1),
	.spics_io_num = -1, // No CS pin
	.queue_size = 1,
	.flags = self->firstbit == MICROPY_PY_MACHINE_SPI_LSB ? SPI_DEVICE_TXBIT_LSBFIRST \| SPI_DEVICE_RXBIT_LSBFIRST : 0,
	.pre_cb = NULL
	};

	//Initialize the SPI bus

	// Select DMA channel based on the hardware SPI host
	int dma_chan = 0;
	if (self->host == HSPI_HOST) {
	dma_chan = 1;
	} else if (self->host == VSPI_HOST) {
	dma_chan = 2;
	}

	ret = spi_bus_initialize(self->host, &buscfg, dma_chan);
	switch (ret) {
	case ESP_ERR_INVALID_ARG:
	mp_raise_msg(&mp_type_OSError, "invalid configuration");
	return;

	case ESP_ERR_INVALID_STATE:
	mp_raise_msg(&mp_type_OSError, "SPI device already in use");
	return;
	}

	ret = spi_bus_add_device(self->host, &devcfg, &self->spi);
	switch (ret) {
	case ESP_ERR_INVALID_ARG:
	mp_raise_msg(&mp_type_OSError, "invalid configuration");
	spi_bus_free(self->host);
	return;

	case ESP_ERR_NO_MEM:
	mp_raise_msg(&mp_type_OSError, "out of memory");
	spi_bus_free(self->host);
	return;

	case ESP_ERR_NOT_FOUND:
	mp_raise_msg(&mp_type_OSError, "no free slots");
	spi_bus_free(self->host);
	return;
	}
	self->state = MACHINE_HW_SPI_STATE_INIT;
	}

	STATIC void machine_hw_spi_deinit(mp_obj_base_t *self_in) {
	machine_hw_spi_obj_t self = (machine_hw_spi_obj_t ) self_in;
	if (self->state == MACHINE_HW_SPI_STATE_INIT) {
	self->state = MACHINE_HW_SPI_STATE_DEINIT;
	machine_hw_spi_deinit_internal(self);
	}
	}

	STATIC void machine_hw_spi_transfer(mp_obj_base_t self_in, size_t len, const uint8_t src, uint8_t *dest) {
	machine_hw_spi_obj_t *self = MP_OBJ_TO_PTR(self_in);

	if (self->state == MACHINE_HW_SPI_STATE_DEINIT) {
	mp_raise_msg(&mp_type_OSError, "transfer on deinitialized SPI");
	return;
	}

	struct spi_transaction_t transaction = { 0 };

	// Round to nearest whole set of bits
	int bits_to_send = len * 8 / self->bits * self->bits;


	if (len <= 4) {
	if (src != NULL) {
	memcpy(&transaction.tx_data, src, len);
	}

	transaction.flags = SPI_TRANS_USE_TXDATA \| SPI_TRANS_USE_RXDATA;
	transaction.length = bits_to_send;
	spi_device_transmit(self->spi, &transaction);

	if (dest != NULL) {
	memcpy(dest, &transaction.rx_data, len);
	}
	} else {
	int offset = 0;
	int bits_remaining = bits_to_send;

	while (bits_remaining) {
	memset(&transaction, 0, sizeof(transaction));

	transaction.length =
	bits_remaining > MP_HW_SPI_MAX_XFER_BITS ? MP_HW_SPI_MAX_XFER_BITS : bits_remaining;

	if (src != NULL) {
	transaction.tx_buffer = src + offset;
	}
	if (dest != NULL) {
	transaction.rx_buffer = dest + offset;
	}

	spi_device_transmit(self->spi, &transaction);
	bits_remaining -= transaction.length;

	// doesn't need ceil(); loop ends when bits_remaining is 0
	offset += transaction.length / 8;
	}
	}
	}

	/******************************************************************************/
	// MicroPython bindings for hw_spi

	STATIC void machine_hw_spi_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
	machine_hw_spi_obj_t *self = MP_OBJ_TO_PTR(self_in);
	mp_printf(print, "SPI(id=%u, baudrate=%u, polarity=%u, phase=%u, bits=%u, firstbit=%u, sck=%d, mosi=%d, miso=%d)",
	self->host, self->baudrate, self->polarity,
	self->phase, self->bits, self->firstbit,
	self->sck, self->mosi, self->miso);
	}

	STATIC void machine_hw_spi_init(mp_obj_base_t self_in, size_t n_args, const mp_obj_t pos_args, mp_map_t *kw_args) {
	machine_hw_spi_obj_t self = (machine_hw_spi_obj_t ) self_in;

	enum { ARG_id, ARG_baudrate, ARG_polarity, ARG_phase, ARG_bits, ARG_firstbit, ARG_sck, ARG_mosi, ARG_miso };
	static const mp_arg_t allowed_args[] = {
	{ MP_QSTR_id, MP_ARG_INT, {.u_int = -1} },
	{ MP_QSTR_baudrate, MP_ARG_INT, {.u_int = -1} },
	{ MP_QSTR_polarity, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = -1} },
	{ MP_QSTR_phase, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = -1} },
	{ MP_QSTR_bits, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = -1} },
	{ MP_QSTR_firstbit, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = -1} },
	{ MP_QSTR_sck, MP_ARG_KW_ONLY \| MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
	{ MP_QSTR_mosi, MP_ARG_KW_ONLY \| MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
	{ MP_QSTR_miso, MP_ARG_KW_ONLY \| MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
	};

	mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
	mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args),
	allowed_args, args);
	int8_t sck, mosi, miso;

	if (args[ARG_sck].u_obj == MP_OBJ_NULL) {
	sck = -2;
	} else if (args[ARG_sck].u_obj == mp_const_none) {
	sck = -1;
	} else {
	sck = machine_pin_get_id(args[ARG_sck].u_obj);
	}

	if (args[ARG_miso].u_obj == MP_OBJ_NULL) {
	miso = -2;
	} else if (args[ARG_miso].u_obj == mp_const_none) {
	miso = -1;
	} else {
	miso = machine_pin_get_id(args[ARG_miso].u_obj);
	}

	if (args[ARG_mosi].u_obj == MP_OBJ_NULL) {
	mosi = -2;
	} else if (args[ARG_mosi].u_obj == mp_const_none) {
	mosi = -1;
	} else {
	mosi = machine_pin_get_id(args[ARG_mosi].u_obj);
	}

	machine_hw_spi_init_internal(self, args[ARG_id].u_int, args[ARG_baudrate].u_int,
	args[ARG_polarity].u_int, args[ARG_phase].u_int, args[ARG_bits].u_int,
	args[ARG_firstbit].u_int, sck, mosi, miso);
	}

	mp_obj_t machine_hw_spi_make_new(const mp_obj_type_t type, size_t n_args, size_t n_kw, const mp_obj_t all_args) {
	enum { ARG_id, ARG_baudrate, ARG_polarity, ARG_phase, ARG_bits, ARG_firstbit, ARG_sck, ARG_mosi, ARG_miso };
	static const mp_arg_t allowed_args[] = {
	{ MP_QSTR_id, MP_ARG_REQUIRED \| MP_ARG_INT, {.u_int = -1} },
	{ MP_QSTR_baudrate, MP_ARG_INT, {.u_int = 500000} },
	{ MP_QSTR_polarity, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = 0} },
	{ MP_QSTR_phase, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = 0} },
	{ MP_QSTR_bits, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = 8} },
	{ MP_QSTR_firstbit, MP_ARG_KW_ONLY \| MP_ARG_INT, {.u_int = MICROPY_PY_MACHINE_SPI_MSB} },
	{ MP_QSTR_sck, MP_ARG_KW_ONLY \| MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
	{ MP_QSTR_mosi, MP_ARG_KW_ONLY \| MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
	{ MP_QSTR_miso, MP_ARG_KW_ONLY \| MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
	};
	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);

	machine_hw_spi_obj_t *self = m_new_obj(machine_hw_spi_obj_t);
	self->base.type = &machine_hw_spi_type;

	machine_hw_spi_init_internal(
	self,
	args[ARG_id].u_int,
	args[ARG_baudrate].u_int,
	args[ARG_polarity].u_int,
	args[ARG_phase].u_int,
	args[ARG_bits].u_int,
	args[ARG_firstbit].u_int,
	args[ARG_sck].u_obj == MP_OBJ_NULL ? -1 : machine_pin_get_id(args[ARG_sck].u_obj),
	args[ARG_mosi].u_obj == MP_OBJ_NULL ? -1 : machine_pin_get_id(args[ARG_mosi].u_obj),
	args[ARG_miso].u_obj == MP_OBJ_NULL ? -1 : machine_pin_get_id(args[ARG_miso].u_obj));

	return MP_OBJ_FROM_PTR(self);
	}

	STATIC const mp_machine_spi_p_t machine_hw_spi_p = {
	.init = machine_hw_spi_init,
	.deinit = machine_hw_spi_deinit,
	.transfer = machine_hw_spi_transfer,
	};

	const mp_obj_type_t machine_hw_spi_type = {
	{ &mp_type_type },
	.name = MP_QSTR_SPI,
	.print = machine_hw_spi_print,
	.make_new = machine_hw_spi_make_new,
	.protocol = &machine_hw_spi_p,
	.locals_dict = (mp_obj_dict_t *) &mp_machine_spi_locals_dict,
	};