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Merged
merged 1 commit into from
Jul 2, 2018
Merged

nrf: Rewrite the I2C common-hal using nrfx #972

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1 change: 1 addition & 0 deletions ports/nrf/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,7 @@ SRC_HAL = $(addprefix hal/,\

SRC_NRFX = $(addprefix nrfx/,\
drivers/src/nrfx_spim.c \
drivers/src/nrfx_twim.c \
)

SRC_C += \
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222 changes: 93 additions & 129 deletions ports/nrf/common-hal/busio/I2C.c
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Expand Up @@ -5,6 +5,7 @@
*
* Copyright (c) 2016 Sandeep Mistry All right reserved.
* Copyright (c) 2017 hathach
* Copyright (c) 2018 Artur Pacholec
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
Expand All @@ -29,67 +30,103 @@
#include "py/mperrno.h"
#include "py/runtime.h"

#include "pins.h"
#include "nrf.h"
#include "nrfx_twim.h"
#include "nrf_gpio.h"

#define INST_NO 0

static uint8_t twi_error_to_mp(const nrfx_err_t err) {
switch (err) {
case NRFX_ERROR_DRV_TWI_ERR_ANACK:
return MP_ENODEV;
case NRFX_ERROR_BUSY:
return MP_EBUSY;
case NRFX_ERROR_DRV_TWI_ERR_DNACK:
case NRFX_ERROR_INVALID_ADDR:
return MP_EIO;
default:
break;
}

return 0;
}

void common_hal_busio_i2c_construct(busio_i2c_obj_t *self, const mcu_pin_obj_t* scl, const mcu_pin_obj_t* sda, uint32_t frequency, uint32_t timeout ) {
if (scl->pin == sda->pin) {
void common_hal_busio_i2c_construct(busio_i2c_obj_t *self, const mcu_pin_obj_t *scl, const mcu_pin_obj_t *sda, uint32_t frequency, uint32_t timeout) {
if (scl->pin == sda->pin)
mp_raise_ValueError("Invalid pins");
}

NRF_GPIO->PIN_CNF[scl->pin] = ((uint32_t)GPIO_PIN_CNF_DIR_Input << GPIO_PIN_CNF_DIR_Pos)
| ((uint32_t)GPIO_PIN_CNF_INPUT_Disconnect << GPIO_PIN_CNF_INPUT_Pos)
| ((uint32_t)GPIO_PIN_CNF_PULL_Disabled << GPIO_PIN_CNF_PULL_Pos)
| ((uint32_t)GPIO_PIN_CNF_DRIVE_S0S1 << GPIO_PIN_CNF_DRIVE_Pos)
| ((uint32_t)GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos);

NRF_GPIO->PIN_CNF[sda->pin] = ((uint32_t)GPIO_PIN_CNF_DIR_Input << GPIO_PIN_CNF_DIR_Pos)
| ((uint32_t)GPIO_PIN_CNF_INPUT_Disconnect << GPIO_PIN_CNF_INPUT_Pos)
| ((uint32_t)GPIO_PIN_CNF_PULL_Disabled << GPIO_PIN_CNF_PULL_Pos)
| ((uint32_t)GPIO_PIN_CNF_DRIVE_S0S1 << GPIO_PIN_CNF_DRIVE_Pos)
| ((uint32_t)GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos);

// 1 for I2C, 0 for SPI
self->twi = NRF_TWIM1;

if ( frequency < 100000 ) {
self->twi->FREQUENCY = TWIM_FREQUENCY_FREQUENCY_K100;
}else if ( frequency < 250000 ) {
self->twi->FREQUENCY = TWIM_FREQUENCY_FREQUENCY_K250;
}else {
self->twi->FREQUENCY = TWIM_FREQUENCY_FREQUENCY_K400;
const nrfx_twim_t instance = NRFX_TWIM_INSTANCE(INST_NO);
self->twim = instance;

nrfx_twim_config_t config = NRFX_TWIM_DEFAULT_CONFIG;
config.scl = NRF_GPIO_PIN_MAP(scl->port, scl->pin);
config.sda = NRF_GPIO_PIN_MAP(sda->port, sda->pin);

// change freq. only if it's less than the default 400K
if (frequency < 100000) {
config.frequency = NRF_TWIM_FREQ_100K;
} else if (frequency < 250000) {
config.frequency = NRF_TWIM_FREQ_250K;
}

self->twi->ENABLE = (TWIM_ENABLE_ENABLE_Enabled << TWIM_ENABLE_ENABLE_Pos);
nrfx_err_t err = nrfx_twim_init(&self->twim, &config, NULL, NULL);
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The config struct is interesting. Its very ASF3 style. They moved away from it because it encodes a bunch of data that's usually the default state of the peripheral once its software reset.

How does this impact code size?

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Actually, I don't think it's that much of an overhead, as the config structs are not that large, they only have the fields that are really needed and I'm not sure if we can trust the peripherals to always be in a known state, so probably best to init the bare minimum always. The benfit of using the drivers instead of the hal is that (in addition to being easier to use), they also have fixes/workarounds for known silicon bugs and and general error handling that we don't have to think about.

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You should measure it. :-)

I looked at the data sheet and there isn't a reset register like the SAMD peripherals have. So it makes sense to set everything.

In general I like this library and using it. I'm just giving you a heads up about our similar experiences with ASF3. Error checking is good but can add overhead if we know a given state but the compiler doesn't recognize. We have plenty of space now so starting with this is fine.


// A soft reset doesn't uninit the driver so we might end up with a invalid state
if (err == NRFX_ERROR_INVALID_STATE) {
nrfx_twim_uninit(&self->twim);
err = nrfx_twim_init(&self->twim, &config, NULL, NULL);
}

self->twi->PSEL.SCL = scl->pin;
self->twi->PSEL.SDA = sda->pin;
if (err != NRFX_SUCCESS)
mp_raise_OSError(MP_EIO);

self->inited = true;
}

bool common_hal_busio_i2c_deinited(busio_i2c_obj_t *self) {
return self->twi->ENABLE == 0;
return !self->inited;
}

void common_hal_busio_i2c_deinit(busio_i2c_obj_t *self) {
if (common_hal_busio_i2c_deinited(self)) {
if (common_hal_busio_i2c_deinited(self))
return;
}

uint8_t scl_pin = self->twi->PSEL.SCL;
uint8_t sda_pin = self->twi->PSEL.SDA;

self->twi->ENABLE = (TWIM_ENABLE_ENABLE_Disabled << TWIM_ENABLE_ENABLE_Pos);
self->twi->PSEL.SCL = (TWIM_PSEL_SCL_CONNECT_Disconnected << TWIM_PSEL_SCL_CONNECT_Pos);
self->twi->PSEL.SDA = (TWIM_PSEL_SDA_CONNECT_Disconnected << TWIM_PSEL_SDA_CONNECT_Pos);
nrfx_twim_uninit(&self->twim);

reset_pin(scl_pin);
reset_pin(sda_pin);
self->inited = false;
}

// nrfx_twim_tx doesn't support 0-length data so we fall back to the hal API
bool common_hal_busio_i2c_probe(busio_i2c_obj_t *self, uint8_t addr) {
// Write no data when just probing
return 0 == common_hal_busio_i2c_write(self, addr, NULL, 0, true);
NRF_TWIM_Type *reg = self->twim.p_twim;
bool found = true;

nrfx_twim_enable(&self->twim);

nrf_twim_address_set(reg, addr);
nrf_twim_tx_buffer_set(reg, NULL, 0);

nrf_twim_task_trigger(reg, NRF_TWIM_TASK_RESUME);

nrf_twim_task_trigger(reg, NRF_TWIM_TASK_STARTTX);
while (nrf_twim_event_check(reg, NRF_TWIM_EVENT_TXSTARTED) == 0 &&
nrf_twim_event_check(reg, NRF_TWIM_EVENT_ERROR) == 0);
nrf_twim_event_clear(reg, NRF_TWIM_EVENT_TXSTARTED);

nrf_twim_task_trigger(reg, NRF_TWIM_TASK_STOP);
while (nrf_twim_event_check(reg, NRF_TWIM_EVENT_STOPPED) == 0);
nrf_twim_event_clear(reg, NRF_TWIM_EVENT_STOPPED);

if (nrf_twim_event_check(reg, NRF_TWIM_EVENT_ERROR)) {
nrf_twim_event_clear(reg, NRF_TWIM_EVENT_ERROR);

nrf_twim_errorsrc_get_and_clear(reg);
found = false;
}

nrfx_twim_disable(&self->twim);

return found;
}

bool common_hal_busio_i2c_try_lock(busio_i2c_obj_t *self) {
Expand All @@ -112,96 +149,23 @@ void common_hal_busio_i2c_unlock(busio_i2c_obj_t *self) {
}

uint8_t common_hal_busio_i2c_write(busio_i2c_obj_t *self, uint16_t addr, const uint8_t *data, size_t len, bool stopBit) {
NRF_TWIM_Type* twi = self->twi;

twi->ADDRESS = addr;
twi->TASKS_RESUME = 1;

twi->TXD.PTR = (uint32_t) data;
twi->TXD.MAXCNT = len;

twi->TASKS_STARTTX = 1;

// Wait for TX started
while(!twi->EVENTS_TXSTARTED && !twi->EVENTS_ERROR) {}
twi->EVENTS_TXSTARTED = 0;

// Wait for TX complete
if ( len )
{
while(!twi->EVENTS_LASTTX && !twi->EVENTS_ERROR) {}
twi->EVENTS_LASTTX = 0x0UL;
}

if (stopBit || twi->EVENTS_ERROR)
{
twi->TASKS_STOP = 0x1UL;
while(!twi->EVENTS_STOPPED);
twi->EVENTS_STOPPED = 0x0UL;
}
else
{
twi->TASKS_SUSPEND = 0x1UL;
while(!twi->EVENTS_SUSPENDED);
twi->EVENTS_SUSPENDED = 0x0UL;
}

if (twi->EVENTS_ERROR)
{
twi->EVENTS_ERROR = 0x0UL;
uint32_t error = twi->ERRORSRC;
twi->ERRORSRC = error;

return error;
}

return 0;
}

uint8_t common_hal_busio_i2c_read(busio_i2c_obj_t *self, uint16_t addr, uint8_t *data, size_t len) {
NRF_TWIM_Type* twi = self->twi;

if(len == 0) return 0;
bool stopBit = true; // should be a parameter
if(len == 0)
return common_hal_busio_i2c_probe(self, addr) ? 0 : MP_ENODEV;

twi->ADDRESS = addr;
twi->TASKS_RESUME = 0x1UL;
nrfx_twim_enable(&self->twim);
const nrfx_err_t err = nrfx_twim_tx(&self->twim, addr, data, len, !stopBit);
nrfx_twim_disable(&self->twim);

twi->RXD.PTR = (uint32_t) data;
twi->RXD.MAXCNT = len;

twi->TASKS_STARTRX = 0x1UL;

while(!twi->EVENTS_RXSTARTED && !twi->EVENTS_ERROR);
twi->EVENTS_RXSTARTED = 0x0UL;

while(!twi->EVENTS_LASTRX && !twi->EVENTS_ERROR);
twi->EVENTS_LASTRX = 0x0UL;

if (stopBit || twi->EVENTS_ERROR)
{
twi->TASKS_STOP = 0x1UL;
while(!twi->EVENTS_STOPPED);
twi->EVENTS_STOPPED = 0x0UL;
}
else
{
twi->TASKS_SUSPEND = 0x1UL;
while(!twi->EVENTS_SUSPENDED);
twi->EVENTS_SUSPENDED = 0x0UL;
}

if (twi->EVENTS_ERROR)
{
twi->EVENTS_ERROR = 0x0UL;
uint32_t error = twi->ERRORSRC;
twi->ERRORSRC = error;
return twi_error_to_mp(err);
}

return error;
}
uint8_t common_hal_busio_i2c_read(busio_i2c_obj_t *self, uint16_t addr, uint8_t *data, size_t len) {
if(len == 0)
return 0;

// number of byte read
// (void) _p_twim->RXD.AMOUNT;
nrfx_twim_enable(&self->twim);
const nrfx_err_t err = nrfx_twim_rx(&self->twim, addr, data, len);
nrfx_twim_disable(&self->twim);

return 0;
return twi_error_to_mp(err);
}
9 changes: 4 additions & 5 deletions ports/nrf/common-hal/busio/I2C.h
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Expand Up @@ -27,16 +27,15 @@
#ifndef MICROPY_INCLUDED_NRF_COMMON_HAL_BUSIO_I2C_H
#define MICROPY_INCLUDED_NRF_COMMON_HAL_BUSIO_I2C_H

#include "common-hal/microcontroller/Pin.h"

//#include "hal/include/hal_i2c_m_sync.h"
#include "nrfx_twim.h"

#include "py/obj.h"

typedef struct {
mp_obj_base_t base;
volatile bool has_lock;
NRF_TWIM_Type* twi;
nrfx_twim_t twim;
bool inited;
bool has_lock;
} busio_i2c_obj_t;

#endif // MICROPY_INCLUDED_NRF_COMMON_HAL_BUSIO_I2C_H
9 changes: 9 additions & 0 deletions ports/nrf/nrfx_config.h
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@@ -1,6 +1,7 @@
#ifndef NRFX_CONFIG_H__
#define NRFX_CONFIG_H__

// SPI
#define NRFX_SPIM_ENABLED 1

#ifdef NRF52840_XXAA
Expand All @@ -12,4 +13,12 @@
#define NRFX_SPIM_DEFAULT_CONFIG_IRQ_PRIORITY 7
#define NRFX_SPIM_MISO_PULL_CFG 1

// TWI aka. I2C
#define NRFX_TWIM_ENABLED 1
#define NRFX_TWIM0_ENABLED 1

#define NRFX_TWIM_DEFAULT_CONFIG_IRQ_PRIORITY 7
#define NRFX_TWIM_DEFAULT_CONFIG_FREQUENCY NRF_TWIM_FREQ_400K
#define NRFX_TWIM_DEFAULT_CONFIG_HOLD_BUS_UNINIT 0

#endif