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author | Joel Challis <git@zvecr.com> | 2021-09-07 16:34:59 +0100 |
---|---|---|
committer | GitHub <noreply@github.com> | 2021-09-07 16:34:59 +0100 |
commit | e7a5c006d9777a4009da934f408961aa2d2e6fb1 (patch) | |
tree | 98c6ca624c08dde5f5d288d405b8eb3a5356d6a6 | |
parent | 2d6635214ab05858271f312619c5447bf317cf51 (diff) | |
download | qmk_firmware-e7a5c006d9777a4009da934f408961aa2d2e6fb1.tar.gz qmk_firmware-e7a5c006d9777a4009da934f408961aa2d2e6fb1.zip |
Refactor use of legacy i2c implementation (#14341)
-rw-r--r-- | keyboards/sx60/i2cmaster.h | 178 | ||||
-rw-r--r-- | keyboards/sx60/matrix.c | 21 | ||||
-rwxr-xr-x | keyboards/sx60/rules.mk | 4 | ||||
-rwxr-xr-x | keyboards/sx60/sx60.c | 31 | ||||
-rwxr-xr-x | keyboards/sx60/sx60.h | 5 | ||||
-rw-r--r-- | keyboards/sx60/twimaster.c | 207 |
6 files changed, 25 insertions, 421 deletions
diff --git a/keyboards/sx60/i2cmaster.h b/keyboards/sx60/i2cmaster.h deleted file mode 100644 index 3917b9e6c..000000000 --- a/keyboards/sx60/i2cmaster.h +++ /dev/null | |||
@@ -1,178 +0,0 @@ | |||
1 | #ifndef _I2CMASTER_H | ||
2 | #define _I2CMASTER_H 1 | ||
3 | /************************************************************************* | ||
4 | * Title: C include file for the I2C master interface | ||
5 | * (i2cmaster.S or twimaster.c) | ||
6 | * Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury | ||
7 | * File: $Id: i2cmaster.h,v 1.10 2005/03/06 22:39:57 Peter Exp $ | ||
8 | * Software: AVR-GCC 3.4.3 / avr-libc 1.2.3 | ||
9 | * Target: any AVR device | ||
10 | * Usage: see Doxygen manual | ||
11 | **************************************************************************/ | ||
12 | |||
13 | #ifdef DOXYGEN | ||
14 | /** | ||
15 | @defgroup pfleury_ic2master I2C Master library | ||
16 | @code #include <i2cmaster.h> @endcode | ||
17 | |||
18 | @brief I2C (TWI) Master Software Library | ||
19 | |||
20 | Basic routines for communicating with I2C slave devices. This single master | ||
21 | implementation is limited to one bus master on the I2C bus. | ||
22 | |||
23 | This I2c library is implemented as a compact assembler software implementation of the I2C protocol | ||
24 | which runs on any AVR (i2cmaster.S) and as a TWI hardware interface for all AVR with built-in TWI hardware (twimaster.c). | ||
25 | Since the API for these two implementations is exactly the same, an application can be linked either against the | ||
26 | software I2C implementation or the hardware I2C implementation. | ||
27 | |||
28 | Use 4.7k pull-up resistor on the SDA and SCL pin. | ||
29 | |||
30 | Adapt the SCL and SDA port and pin definitions and eventually the delay routine in the module | ||
31 | i2cmaster.S to your target when using the software I2C implementation ! | ||
32 | |||
33 | Adjust the CPU clock frequence F_CPU in twimaster.c or in the Makfile when using the TWI hardware implementaion. | ||
34 | |||
35 | @note | ||
36 | The module i2cmaster.S is based on the Atmel Application Note AVR300, corrected and adapted | ||
37 | to GNU assembler and AVR-GCC C call interface. | ||
38 | Replaced the incorrect quarter period delays found in AVR300 with | ||
39 | half period delays. | ||
40 | |||
41 | @author Peter Fleury pfleury@gmx.ch http://jump.to/fleury | ||
42 | |||
43 | @par API Usage Example | ||
44 | The following code shows typical usage of this library, see example test_i2cmaster.c | ||
45 | |||
46 | @code | ||
47 | |||
48 | #include <i2cmaster.h> | ||
49 | |||
50 | |||
51 | #define Dev24C02 0xA2 // device address of EEPROM 24C02, see datasheet | ||
52 | |||
53 | int main(void) | ||
54 | { | ||
55 | unsigned char ret; | ||
56 | |||
57 | i2c_init(); // initialize I2C library | ||
58 | |||
59 | // write 0x75 to EEPROM address 5 (Byte Write) | ||
60 | i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode | ||
61 | i2c_write(0x05); // write address = 5 | ||
62 | i2c_write(0x75); // write value 0x75 to EEPROM | ||
63 | i2c_stop(); // set stop conditon = release bus | ||
64 | |||
65 | |||
66 | // read previously written value back from EEPROM address 5 | ||
67 | i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode | ||
68 | |||
69 | i2c_write(0x05); // write address = 5 | ||
70 | i2c_rep_start(Dev24C02+I2C_READ); // set device address and read mode | ||
71 | |||
72 | ret = i2c_readNak(); // read one byte from EEPROM | ||
73 | i2c_stop(); | ||
74 | |||
75 | for(;;); | ||
76 | } | ||
77 | @endcode | ||
78 | |||
79 | */ | ||
80 | #endif /* DOXYGEN */ | ||
81 | |||
82 | /**@{*/ | ||
83 | |||
84 | #if (__GNUC__ * 100 + __GNUC_MINOR__) < 304 | ||
85 | #error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !" | ||
86 | #endif | ||
87 | |||
88 | #include <avr/io.h> | ||
89 | |||
90 | /** defines the data direction (reading from I2C device) in i2c_start(),i2c_rep_start() */ | ||
91 | #define I2C_READ 1 | ||
92 | |||
93 | /** defines the data direction (writing to I2C device) in i2c_start(),i2c_rep_start() */ | ||
94 | #define I2C_WRITE 0 | ||
95 | |||
96 | |||
97 | /** | ||
98 | @brief initialize the I2C master interace. Need to be called only once | ||
99 | @param void | ||
100 | @return none | ||
101 | */ | ||
102 | extern void i2c_init(void); | ||
103 | |||
104 | |||
105 | /** | ||
106 | @brief Terminates the data transfer and releases the I2C bus | ||
107 | @param void | ||
108 | @return none | ||
109 | */ | ||
110 | extern void i2c_stop(void); | ||
111 | |||
112 | |||
113 | /** | ||
114 | @brief Issues a start condition and sends address and transfer direction | ||
115 | |||
116 | @param addr address and transfer direction of I2C device | ||
117 | @retval 0 device accessible | ||
118 | @retval 1 failed to access device | ||
119 | */ | ||
120 | extern unsigned char i2c_start(unsigned char addr); | ||
121 | |||
122 | |||
123 | /** | ||
124 | @brief Issues a repeated start condition and sends address and transfer direction | ||
125 | |||
126 | @param addr address and transfer direction of I2C device | ||
127 | @retval 0 device accessible | ||
128 | @retval 1 failed to access device | ||
129 | */ | ||
130 | extern unsigned char i2c_rep_start(unsigned char addr); | ||
131 | |||
132 | |||
133 | /** | ||
134 | @brief Issues a start condition and sends address and transfer direction | ||
135 | |||
136 | If device is busy, use ack polling to wait until device ready | ||
137 | @param addr address and transfer direction of I2C device | ||
138 | @return none | ||
139 | */ | ||
140 | extern void i2c_start_wait(unsigned char addr); | ||
141 | |||
142 | |||
143 | /** | ||
144 | @brief Send one byte to I2C device | ||
145 | @param data byte to be transfered | ||
146 | @retval 0 write successful | ||
147 | @retval 1 write failed | ||
148 | */ | ||
149 | extern unsigned char i2c_write(unsigned char data); | ||
150 | |||
151 | |||
152 | /** | ||
153 | @brief read one byte from the I2C device, request more data from device | ||
154 | @return byte read from I2C device | ||
155 | */ | ||
156 | extern unsigned char i2c_readAck(void); | ||
157 | |||
158 | /** | ||
159 | @brief read one byte from the I2C device, read is followed by a stop condition | ||
160 | @return byte read from I2C device | ||
161 | */ | ||
162 | extern unsigned char i2c_readNak(void); | ||
163 | |||
164 | /** | ||
165 | @brief read one byte from the I2C device | ||
166 | |||
167 | Implemented as a macro, which calls either i2c_readAck or i2c_readNak | ||
168 | |||
169 | @param ack 1 send ack, request more data from device<br> | ||
170 | 0 send nak, read is followed by a stop condition | ||
171 | @return byte read from I2C device | ||
172 | */ | ||
173 | extern unsigned char i2c_read(unsigned char ack); | ||
174 | #define i2c_read(ack) (ack) ? i2c_readAck() : i2c_readNak(); | ||
175 | |||
176 | |||
177 | /**@}*/ | ||
178 | #endif | ||
diff --git a/keyboards/sx60/matrix.c b/keyboards/sx60/matrix.c index 6fa0dd145..b7dc25425 100644 --- a/keyboards/sx60/matrix.c +++ b/keyboards/sx60/matrix.c | |||
@@ -243,15 +243,11 @@ static bool read_cols_on_row(matrix_row_t current_matrix[], uint8_t current_row) | |||
243 | /* if there was an error */ | 243 | /* if there was an error */ |
244 | return 0; | 244 | return 0; |
245 | } else { | 245 | } else { |
246 | uint16_t data = 0; | 246 | uint8_t data = 0; |
247 | mcp23018_status = i2c_start(I2C_ADDR_WRITE); if (mcp23018_status) goto out; | 247 | mcp23018_status = i2c_readReg(I2C_ADDR, GPIOA, &data, 1, I2C_TIMEOUT); |
248 | mcp23018_status = i2c_write(GPIOA); if (mcp23018_status) goto out; | 248 | if (!mcp23018_status) { |
249 | mcp23018_status = i2c_start(I2C_ADDR_READ); if (mcp23018_status) goto out; | 249 | current_matrix[current_row] |= (~((uint16_t)data) << 8); |
250 | data = i2c_readNak(); | 250 | } |
251 | data = ~data; | ||
252 | out: | ||
253 | i2c_stop(); | ||
254 | current_matrix[current_row] |= (data << 8); | ||
255 | } | 251 | } |
256 | 252 | ||
257 | /* For each col... */ | 253 | /* For each col... */ |
@@ -278,11 +274,8 @@ static void select_row(uint8_t row) | |||
278 | /* set active row low : 0 | 274 | /* set active row low : 0 |
279 | set active row output : 1 | 275 | set active row output : 1 |
280 | set other rows hi-Z : 1 */ | 276 | set other rows hi-Z : 1 */ |
281 | mcp23018_status = i2c_start(I2C_ADDR_WRITE); if (mcp23018_status) goto out; | 277 | uint8_t port = 0xFF & ~(1<<abs(row-4)); |
282 | mcp23018_status = i2c_write(GPIOB); if (mcp23018_status) goto out; | 278 | mcp23018_status = i2c_writeReg(I2C_ADDR, GPIOB, &port, 1, I2C_TIMEOUT); |
283 | mcp23018_status = i2c_write(0xFF & ~(1<<abs(row-4))); if (mcp23018_status) goto out; | ||
284 | out: | ||
285 | i2c_stop(); | ||
286 | } | 279 | } |
287 | 280 | ||
288 | uint8_t pin = row_pins[row]; | 281 | uint8_t pin = row_pins[row]; |
diff --git a/keyboards/sx60/rules.mk b/keyboards/sx60/rules.mk index 8c2ad5259..1550b65c1 100755 --- a/keyboards/sx60/rules.mk +++ b/keyboards/sx60/rules.mk | |||
@@ -27,5 +27,5 @@ RGBLIGHT_ENABLE = no | |||
27 | CUSTOM_MATRIX = yes | 27 | CUSTOM_MATRIX = yes |
28 | 28 | ||
29 | # project specific files | 29 | # project specific files |
30 | SRC = twimaster.c \ | 30 | QUANTUM_LIB_SRC += i2c_master.c |
31 | matrix.c | 31 | SRC += matrix.c |
diff --git a/keyboards/sx60/sx60.c b/keyboards/sx60/sx60.c index ede8c07e9..cb7f2b88f 100755 --- a/keyboards/sx60/sx60.c +++ b/keyboards/sx60/sx60.c | |||
@@ -1,5 +1,5 @@ | |||
1 | #include "sx60.h" | 1 | #include "sx60.h" |
2 | #include "i2cmaster.h" | 2 | #include "i2c_master.h" |
3 | 3 | ||
4 | 4 | ||
5 | bool i2c_initialized = 0; | 5 | bool i2c_initialized = 0; |
@@ -18,21 +18,18 @@ uint8_t init_mcp23018(void) { | |||
18 | 18 | ||
19 | /* B Pins are Row, A pins are Columns | 19 | /* B Pins are Row, A pins are Columns |
20 | Set them to output */ | 20 | Set them to output */ |
21 | mcp23018_status = i2c_start(I2C_ADDR_WRITE); if (mcp23018_status) goto out; | 21 | static uint8_t direction[2] = { |
22 | mcp23018_status = i2c_write(IODIRA); if (mcp23018_status) goto out; | 22 | 0b11111111, |
23 | mcp23018_status = i2c_write(0b11111111); if (mcp23018_status) goto out; | 23 | 0b00000000, |
24 | /* Now write to IODIRB */ | 24 | }; |
25 | mcp23018_status = i2c_write(0b00000000); if (mcp23018_status) goto out; | 25 | static uint8_t pullup[2] = { |
26 | i2c_stop(); | 26 | 0b11111111, |
27 | 27 | 0b00000000, | |
28 | mcp23018_status = i2c_start(I2C_ADDR_WRITE); if (mcp23018_status) goto out; | 28 | }; |
29 | mcp23018_status = i2c_write(GPPUA); if (mcp23018_status) goto out; | 29 | |
30 | mcp23018_status = i2c_write(0b11111111); if (mcp23018_status) goto out; | 30 | mcp23018_status = i2c_writeReg(I2C_ADDR, IODIRA, direction, 2, I2C_TIMEOUT); |
31 | /* Now write to GPPUB */ | 31 | if (mcp23018_status) return mcp23018_status; |
32 | mcp23018_status = i2c_write(0b00000000); if (mcp23018_status) goto out; | 32 | |
33 | 33 | mcp23018_status = i2c_writeReg(I2C_ADDR, GPPUA, pullup, 2, I2C_TIMEOUT); | |
34 | out: | ||
35 | i2c_stop(); | ||
36 | |||
37 | return mcp23018_status; | 34 | return mcp23018_status; |
38 | } | 35 | } |
diff --git a/keyboards/sx60/sx60.h b/keyboards/sx60/sx60.h index 8ead53ee0..507bddf7b 100755 --- a/keyboards/sx60/sx60.h +++ b/keyboards/sx60/sx60.h | |||
@@ -4,13 +4,12 @@ | |||
4 | #include "quantum.h" | 4 | #include "quantum.h" |
5 | #include <stdint.h> | 5 | #include <stdint.h> |
6 | #include <stdbool.h> | 6 | #include <stdbool.h> |
7 | #include "i2cmaster.h" | 7 | #include "i2c_master.h" |
8 | #include <util/delay.h> | 8 | #include <util/delay.h> |
9 | 9 | ||
10 | /* I2C aliases and register addresses (see "mcp23018.md") */ | 10 | /* I2C aliases and register addresses (see "mcp23018.md") */ |
11 | #define I2C_ADDR 0b0100000 | 11 | #define I2C_ADDR 0b0100000 |
12 | #define I2C_ADDR_WRITE ( (I2C_ADDR<<1) | I2C_WRITE ) | 12 | #define I2C_TIMEOUT 100 |
13 | #define I2C_ADDR_READ ( (I2C_ADDR<<1) | I2C_READ ) | ||
14 | #define IODIRA 0x00 /* i/o direction register */ | 13 | #define IODIRA 0x00 /* i/o direction register */ |
15 | #define IODIRB 0x01 | 14 | #define IODIRB 0x01 |
16 | #define GPPUA 0x0C /* GPIO pull-up resistor register */ | 15 | #define GPPUA 0x0C /* GPIO pull-up resistor register */ |
diff --git a/keyboards/sx60/twimaster.c b/keyboards/sx60/twimaster.c deleted file mode 100644 index 30d8c24bf..000000000 --- a/keyboards/sx60/twimaster.c +++ /dev/null | |||
@@ -1,207 +0,0 @@ | |||
1 | /************************************************************************* | ||
2 | * Title: I2C master library using hardware TWI interface | ||
3 | * Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury | ||
4 | * File: $Id: twimaster.c,v 1.3 2005/07/02 11:14:21 Peter Exp $ | ||
5 | * Software: AVR-GCC 3.4.3 / avr-libc 1.2.3 | ||
6 | * Target: any AVR device with hardware TWI | ||
7 | * Usage: API compatible with I2C Software Library i2cmaster.h | ||
8 | **************************************************************************/ | ||
9 | #include <inttypes.h> | ||
10 | #include <compat/twi.h> | ||
11 | |||
12 | #include <i2cmaster.h> | ||
13 | |||
14 | /* define CPU frequency in Hz here if not defined in Makefile */ | ||
15 | #ifndef F_CPU | ||
16 | #define F_CPU 16000000UL | ||
17 | #endif | ||
18 | |||
19 | /* I2C clock in Hz */ | ||
20 | #define SCL_CLOCK 400000L | ||
21 | |||
22 | |||
23 | /************************************************************************* | ||
24 | Initialization of the I2C bus interface. Need to be called only once | ||
25 | *************************************************************************/ | ||
26 | void i2c_init(void) | ||
27 | { | ||
28 | /* initialize TWI clock | ||
29 | * minimal values in Bit Rate Register (TWBR) and minimal Prescaler | ||
30 | * bits in the TWI Status Register should give us maximal possible | ||
31 | * I2C bus speed - about 444 kHz | ||
32 | * | ||
33 | * for more details, see 20.5.2 in ATmega16/32 secification | ||
34 | */ | ||
35 | |||
36 | TWSR = 0; /* no prescaler */ | ||
37 | TWBR = 10; /* must be >= 10 for stable operation */ | ||
38 | |||
39 | }/* i2c_init */ | ||
40 | |||
41 | |||
42 | /************************************************************************* | ||
43 | Issues a start condition and sends address and transfer direction. | ||
44 | return 0 = device accessible, 1= failed to access device | ||
45 | *************************************************************************/ | ||
46 | unsigned char i2c_start(unsigned char address) | ||
47 | { | ||
48 | uint8_t twst; | ||
49 | |||
50 | /* send START condition */ | ||
51 | TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN); | ||
52 | |||
53 | /* wait until transmission completed */ | ||
54 | while(!(TWCR & (1<<TWINT))); | ||
55 | |||
56 | /* check value of TWI Status Register. Mask prescaler bits. */ | ||
57 | twst = TW_STATUS & 0xF8; | ||
58 | if ( (twst != TW_START) && (twst != TW_REP_START)) return 1; | ||
59 | |||
60 | /* send device address */ | ||
61 | TWDR = address; | ||
62 | TWCR = (1<<TWINT) | (1<<TWEN); | ||
63 | |||
64 | /* wail until transmission completed and ACK/NACK has been received */ | ||
65 | while(!(TWCR & (1<<TWINT))); | ||
66 | |||
67 | /* check value of TWI Status Register. Mask prescaler bits. */ | ||
68 | twst = TW_STATUS & 0xF8; | ||
69 | if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1; | ||
70 | |||
71 | return 0; | ||
72 | |||
73 | }/* i2c_start */ | ||
74 | |||
75 | |||
76 | /************************************************************************* | ||
77 | Issues a start condition and sends address and transfer direction. | ||
78 | If device is busy, use ack polling to wait until device is ready | ||
79 | |||
80 | Input: address and transfer direction of I2C device | ||
81 | *************************************************************************/ | ||
82 | void i2c_start_wait(unsigned char address) | ||
83 | { | ||
84 | uint8_t twst; | ||
85 | |||
86 | |||
87 | while ( 1 ) | ||
88 | { | ||
89 | /* send START condition */ | ||
90 | TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN); | ||
91 | |||
92 | /* wait until transmission completed */ | ||
93 | while(!(TWCR & (1<<TWINT))); | ||
94 | |||
95 | /* check value of TWI Status Register. Mask prescaler bits. */ | ||
96 | twst = TW_STATUS & 0xF8; | ||
97 | if ( (twst != TW_START) && (twst != TW_REP_START)) continue; | ||
98 | |||
99 | /* send device address */ | ||
100 | TWDR = address; | ||
101 | TWCR = (1<<TWINT) | (1<<TWEN); | ||
102 | |||
103 | /* wail until transmission completed */ | ||
104 | while(!(TWCR & (1<<TWINT))); | ||
105 | |||
106 | /* check value of TWI Status Register. Mask prescaler bits. */ | ||
107 | twst = TW_STATUS & 0xF8; | ||
108 | if ( (twst == TW_MT_SLA_NACK )||(twst ==TW_MR_DATA_NACK) ) | ||
109 | { | ||
110 | /* device busy, send stop condition to terminate write operation */ | ||
111 | TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO); | ||
112 | |||
113 | /* wait until stop condition is executed and bus released */ | ||
114 | while(TWCR & (1<<TWSTO)); | ||
115 | |||
116 | continue; | ||
117 | } | ||
118 | |||
119 | break; | ||
120 | } | ||
121 | |||
122 | }/* i2c_start_wait */ | ||
123 | |||
124 | |||
125 | /************************************************************************* | ||
126 | Issues a repeated start condition and sends address and transfer direction | ||
127 | |||
128 | Input: address and transfer direction of I2C device | ||
129 | |||
130 | Return: 0 device accessible | ||
131 | 1 failed to access device | ||
132 | *************************************************************************/ | ||
133 | unsigned char i2c_rep_start(unsigned char address) | ||
134 | { | ||
135 | return i2c_start( address ); | ||
136 | |||
137 | }/* i2c_rep_start */ | ||
138 | |||
139 | |||
140 | /************************************************************************* | ||
141 | Terminates the data transfer and releases the I2C bus | ||
142 | *************************************************************************/ | ||
143 | void i2c_stop(void) | ||
144 | { | ||
145 | /* send stop condition */ | ||
146 | TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO); | ||
147 | |||
148 | /* wait until stop condition is executed and bus released */ | ||
149 | while(TWCR & (1<<TWSTO)); | ||
150 | |||
151 | }/* i2c_stop */ | ||
152 | |||
153 | |||
154 | /************************************************************************* | ||
155 | Send one byte to I2C device | ||
156 | |||
157 | Input: byte to be transfered | ||
158 | Return: 0 write successful | ||
159 | 1 write failed | ||
160 | *************************************************************************/ | ||
161 | unsigned char i2c_write( unsigned char data ) | ||
162 | { | ||
163 | uint8_t twst; | ||
164 | |||
165 | /* send data to the previously addressed device */ | ||
166 | TWDR = data; | ||
167 | TWCR = (1<<TWINT) | (1<<TWEN); | ||
168 | |||
169 | /* wait until transmission completed */ | ||
170 | while(!(TWCR & (1<<TWINT))); | ||
171 | |||
172 | /* check value of TWI Status Register. Mask prescaler bits */ | ||
173 | twst = TW_STATUS & 0xF8; | ||
174 | if( twst != TW_MT_DATA_ACK) return 1; | ||
175 | return 0; | ||
176 | |||
177 | }/* i2c_write */ | ||
178 | |||
179 | |||
180 | /************************************************************************* | ||
181 | Read one byte from the I2C device, request more data from device | ||
182 | |||
183 | Return: byte read from I2C device | ||
184 | *************************************************************************/ | ||
185 | unsigned char i2c_readAck(void) | ||
186 | { | ||
187 | TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA); | ||
188 | while(!(TWCR & (1<<TWINT))); | ||
189 | |||
190 | return TWDR; | ||
191 | |||
192 | }/* i2c_readAck */ | ||
193 | |||
194 | |||
195 | /************************************************************************* | ||
196 | Read one byte from the I2C device, read is followed by a stop condition | ||
197 | |||
198 | Return: byte read from I2C device | ||
199 | *************************************************************************/ | ||
200 | unsigned char i2c_readNak(void) | ||
201 | { | ||
202 | TWCR = (1<<TWINT) | (1<<TWEN); | ||
203 | while(!(TWCR & (1<<TWINT))); | ||
204 | |||
205 | return TWDR; | ||
206 | |||
207 | }/* i2c_readNak */ | ||