diff options
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); +} | 
