43 lines
1.9 KiB
C
43 lines
1.9 KiB
C
/* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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/* This library handles the Two-Wire Interface (TWI)/Inter-Integrated Circuit (I²C) configuration */
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/* TWI/I2C clock speed, in Hz */
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#define F_TWI 100000UL
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/*
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* Maximal number of iterations to wait for a device to respond for a selection
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* Should be large enough to allow for a pending write to* complete, but low enough to properly abort an infinite loop in case a slave is broken or not present at all.
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* With 100 kHz TWI clock, transfering the start condition and SLA+R/W packet takes about 10 µs.
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* The longest write period is supposed to not exceed ~ 10 ms.
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* Thus, normal operation should not require more than 100 iterations to get the device to respond to a selection.
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*/
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#define MAX_ITER 400
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/* card (slave) address (7 MSB) */
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#define SLA 0xA0
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/* initialize 2-wire interface */
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void twi_init(void);
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/* read <len> bytes inyo <buf> using 2-wire interface, starting at <addr>
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* returns if it succeeded
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* 16 bits address is not supported
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*/
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bool twi_read_bytes(uint8_t addr, uint8_t len, uint8_t *buf);
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/* write <len> bytes from <buf> on 2-wire interface starting at <addr>
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* returns if it successed
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* 16 bits address is not supported
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* ensure yourself the size of pages to be written
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*/
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bool twi_write_bytes(uint8_t addr, uint8_t len, uint8_t *buf);
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