diff options
author | Nick Brassel <nick@tzarc.org> | 2021-08-29 08:20:25 +1000 |
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committer | Nick Brassel <nick@tzarc.org> | 2021-08-29 08:20:25 +1000 |
commit | f061ca497464fe85284906fb163a33eaee7a91ef (patch) | |
tree | 33ef1bfb529aed382e8526c607c4e18717f92571 /platforms/avr/drivers/i2c_slave.c | |
parent | ff65185dec6f97be1eb49f17cea526a0d0bbf3d6 (diff) | |
parent | 4bad375d7c09d949a9dcdd4feba147c9c7a67ec6 (diff) |
Breaking changes develop merge to master, 2021Q3 edition. (#14196)
Diffstat (limited to 'platforms/avr/drivers/i2c_slave.c')
-rw-r--r-- | platforms/avr/drivers/i2c_slave.c | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/platforms/avr/drivers/i2c_slave.c b/platforms/avr/drivers/i2c_slave.c new file mode 100644 index 0000000000..2907f164c0 --- /dev/null +++ b/platforms/avr/drivers/i2c_slave.c @@ -0,0 +1,111 @@ +/* Copyright (C) 2019 Elia Ritterbusch + + + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +/* Library made by: g4lvanix + * GitHub repository: https://github.com/g4lvanix/I2C-slave-lib + */ + +#include <stddef.h> +#include <avr/io.h> +#include <util/twi.h> +#include <avr/interrupt.h> +#include <stdbool.h> + +#include "i2c_slave.h" + +#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS) +# include "transactions.h" + +static volatile bool is_callback_executor = false; +#endif // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS) + +volatile uint8_t i2c_slave_reg[I2C_SLAVE_REG_COUNT]; + +static volatile uint8_t buffer_address; +static volatile bool slave_has_register_set = false; + +void i2c_slave_init(uint8_t address) { + // load address into TWI address register + TWAR = address; + // set the TWCR to enable address matching and enable TWI, clear TWINT, enable TWI interrupt + TWCR = (1 << TWIE) | (1 << TWEA) | (1 << TWINT) | (1 << TWEN); +} + +void i2c_slave_stop(void) { + // clear acknowledge and enable bits + TWCR &= ~((1 << TWEA) | (1 << TWEN)); +} + +ISR(TWI_vect) { + uint8_t ack = 1; + + switch (TW_STATUS) { + case TW_SR_SLA_ACK: + // The device is now a slave receiver + slave_has_register_set = false; +#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS) + is_callback_executor = false; +#endif // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS) + break; + + case TW_SR_DATA_ACK: + // This device is a slave receiver and has received data + // First byte is the location then the bytes will be writen in buffer with auto-increment + if (!slave_has_register_set) { + buffer_address = TWDR; + + if (buffer_address >= I2C_SLAVE_REG_COUNT) { // address out of bounds dont ack + ack = 0; + buffer_address = 0; + } + slave_has_register_set = true; // address has been received now fill in buffer + +#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS) + // Work out if we're attempting to execute a callback + is_callback_executor = buffer_address == split_transaction_table[I2C_EXECUTE_CALLBACK].initiator2target_offset; +#endif // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS) + } else { + i2c_slave_reg[buffer_address] = TWDR; + buffer_address++; + +#if defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS) + // If we're intending to execute a transaction callback, do so, as we've just received the transaction ID + if (is_callback_executor) { + split_transaction_desc_t *trans = &split_transaction_table[split_shmem->transaction_id]; + if (trans->slave_callback) { + trans->slave_callback(trans->initiator2target_buffer_size, split_trans_initiator2target_buffer(trans), trans->target2initiator_buffer_size, split_trans_target2initiator_buffer(trans)); + } + } +#endif // defined(USE_I2C) && defined(SPLIT_COMMON_TRANSACTIONS) + } + break; + + case TW_ST_SLA_ACK: + case TW_ST_DATA_ACK: + // This device is a slave transmitter and master has requested data + TWDR = i2c_slave_reg[buffer_address]; + buffer_address++; + break; + + case TW_BUS_ERROR: + // We got an error, reset i2c + TWCR = 0; + default: + break; + } + + // Reset i2c state machine to be ready for next interrupt + TWCR |= (1 << TWIE) | (1 << TWINT) | (ack << TWEA) | (1 << TWEN); +} |