4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2003, 2004, 2005 Develer S.r.l. (http://www.develer.com/)
33 * \brief Driver for the AVR ATMega TWI (implementation)
37 * \author Stefano Fedrigo <aleph@develer.com>
38 * \author Bernardo Innocenti <bernie@develer.com>
43 *#* Revision 1.8 2007/06/07 14:35:12 batt
44 *#* Merge from project_ks.
46 *#* Revision 1.7 2006/07/19 12:56:26 bernie
47 *#* Convert to new Doxygen style.
49 *#* Revision 1.6 2006/03/20 17:49:50 bernie
50 *#* Make the TWI driver more generic to work with devices other than EEPROMS.
52 *#* Revision 1.5 2005/11/27 23:33:40 bernie
53 *#* Use appconfig.h instead of cfg/config.h.
55 *#* Revision 1.4 2005/04/11 19:10:28 bernie
56 *#* Include top-level headers from cfg/ subdir.
58 *#* Revision 1.3 2005/03/01 23:26:00 bernie
61 *#* Revision 1.2 2005/01/25 08:36:56 bernie
62 *#* CONFIG_TWI_FREQ: New config param.
64 *#* Revision 1.1 2005/01/06 16:09:40 aleph
65 *#* Split twi/eeprom functions from eeprom module in separate twi module
71 #include <cfg/debug.h>
73 #include <cfg/macros.h> // BV()
74 #include <hw_cpu.h> /* CLOCK_FREQ */
75 #include <appconfig.h>
77 #include <compat/twi.h>
80 /* Wait for TWINT flag set: bus is ready */
81 #define WAIT_TWI_READY do {} while (!(TWCR & BV(TWINT)))
83 #define READ_BIT BV(0)
87 * Send START condition on the bus.
89 * \return true on success, false otherwise.
91 static bool twi_start(void)
93 TWCR = BV(TWINT) | BV(TWSTA) | BV(TWEN);
96 if (TW_STATUS == TW_START || TW_STATUS == TW_REP_START)
99 kprintf("!TW_(REP)START: %x\n", TWSR);
105 * Send START condition and select slave for write.
106 * \c id is the device id comprehensive of address left shifted by 1.
107 * The LSB of \c id is ignored and reset to 0 for write operation.
109 * \return true on success, false otherwise.
111 bool twi_start_w(uint8_t id)
114 * Loop on the select write sequence: when the eeprom is busy
115 * writing previously sent data it will reply to the SLA_W
116 * control byte with a NACK. In this case, we must
117 * keep trying until the eeprom responds with an ACK.
121 TWDR = id & ~READ_BIT;
122 TWCR = BV(TWINT) | BV(TWEN);
125 if (TW_STATUS == TW_MT_SLA_ACK)
127 else if (TW_STATUS != TW_MT_SLA_NACK)
129 kprintf("!TW_MT_SLA_(N)ACK: %x\n", TWSR);
139 * Send START condition and select slave for read.
140 * \c id is the device id comprehensive of address left shifted by 1.
141 * The LSB of \c id is ignored and set to 1 for read operation.
143 * \return true on success, false otherwise.
145 bool twi_start_r(uint8_t id)
149 TWDR = id | READ_BIT;
150 TWCR = BV(TWINT) | BV(TWEN);
153 if (TW_STATUS == TW_MR_SLA_ACK)
156 kprintf("!TW_MR_SLA_ACK: %x\n", TWSR);
164 * Send STOP condition.
168 TWCR = BV(TWINT) | BV(TWEN) | BV(TWSTO);
173 * Put a single byte in master transmitter mode
174 * to the selected slave device through the TWI bus.
176 * \return true on success, false on error.
178 bool twi_put(const uint8_t data)
181 TWCR = BV(TWINT) | BV(TWEN);
183 if (TW_STATUS != TW_MT_DATA_ACK)
185 kprintf("!TW_MT_DATA_ACK: %x\n", TWSR);
193 * Send a sequence of bytes in master transmitter mode
194 * to the selected slave device through the TWI bus.
196 * \return true on success, false on error.
198 bool twi_send(const void *_buf, size_t count)
200 const uint8_t *buf = (const uint8_t *)_buf;
204 if (!twi_put(*buf++))
212 * Receive a sequence of one or more bytes from the
213 * selected slave device in master receive mode through
216 * Received data is placed in \c buf.
218 * \return true on success, false on error
220 bool twi_recv(void *_buf, size_t count)
222 uint8_t *buf = (uint8_t *)_buf;
225 * When reading the last byte the TWEA bit is not
226 * set, and the eeprom should answer with NACK
230 TWCR = BV(TWINT) | BV(TWEN) | (count ? BV(TWEA) : 0);
235 if (TW_STATUS != TW_MR_DATA_ACK)
237 kprintf("!TW_MR_DATA_ACK: %x\n", TWSR);
243 if (TW_STATUS != TW_MR_DATA_NACK)
245 kprintf("!TW_MR_DATA_NACK: %x\n", TWSR);
257 * Initialize TWI module.
263 * This is pretty useless according to AVR's datasheet,
264 * but it helps us driving the TWI data lines on boards
265 * where the bus pull-up resistors are missing. This is
266 * probably due to some unwanted interaction between the
267 * port pin and the TWI lines.
269 #if CPU_AVR_ATMEGA64 || CPU_AVR_ATMEGA128 || CPU_AVR_ATMEGA1281
270 PORTD |= BV(PD0) | BV(PD1);
271 DDRD |= BV(PD0) | BV(PD1);
272 #elif CPU_AVR_ATMEGA8
273 PORTC |= BV(PC4) | BV(PC5);
274 DDRC |= BV(PC4) | BV(PC5);
276 #error Unsupported architecture
281 * F = CLOCK_FREQ / (16 + 2*TWBR * 4^TWPS)
283 #ifndef CONFIG_TWI_FREQ
284 #warning Using default value of 300000L for CONFIG_TWI_FREQ
285 #define CONFIG_TWI_FREQ 300000L /* ~300 kHz */
287 #define TWI_PRESC 1 /* 4 ^ TWPS */
289 TWBR = (CLOCK_FREQ / (2 * CONFIG_TWI_FREQ * TWI_PRESC)) - (8 / TWI_PRESC);