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-rw-r--r--keyboards/lfkeyboards/TWIlib.c283
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1/*
2 * TWIlib.c
3 *
4 * Created: 6/01/2014 10:41:33 PM
5 * Author: Chris Herring
6 */
7
8#include <avr/io.h>
9#include <avr/interrupt.h>
10#include "TWIlib.h"
11#include "util/delay.h"
12#include "print.h"
13
14void TWIInit()
15{
16 TWIInfo.mode = Ready;
17 TWIInfo.errorCode = 0xFF;
18 TWIInfo.repStart = 0;
19 // Set pre-scalers (no pre-scaling)
20 TWSR = 0;
21 // Set bit rate
22 TWBR = ((F_CPU / TWI_FREQ) - 16) / 2;
23 // Enable TWI and interrupt
24 TWCR = (1 << TWIE) | (1 << TWEN);
25}
26
27uint8_t isTWIReady()
28{
29 if ( (TWIInfo.mode == Ready) | (TWIInfo.mode == RepeatedStartSent) )
30 {
31 return 1;
32 }
33 else
34 {
35 if(TWIInfo.mode == Initializing){
36 switch(TWIInfo.errorCode){
37 case TWI_SUCCESS:
38 case TWI_NO_RELEVANT_INFO:
39 break;
40 case TWI_LOST_ARBIT:
41 case TWI_MT_DATA_NACK:
42 // Some kind of I2C error, reset and re-init
43 xprintf("I2C init error: %d\n", TWIInfo.errorCode);
44 TWCR = (1 << TWINT)|(1 << TWSTO);
45 TWIInit();
46 break;
47 default:
48 xprintf("Other i2c init error: %d\n", TWIInfo.errorCode);
49 }
50 }
51 return 0;
52 }
53}
54
55
56void TWITransmitData(void *const TXdata, uint8_t dataLen, uint8_t repStart, uint8_t blocking)
57{
58 // Wait until ready
59 while (!isTWIReady()) {_delay_us(1);}
60 // Reset the I2C stuff
61 TWCR = (1 << TWINT)|(1 << TWSTO);
62 TWIInit();
63 // Set repeated start mode
64 TWIInfo.repStart = repStart;
65 // Copy transmit info to global variables
66 TWITransmitBuffer = (uint8_t *)TXdata;
67 TXBuffLen = dataLen;
68 TXBuffIndex = 0;
69
70 // If a repeated start has been sent, then devices are already listening for an address
71 // and another start does not need to be sent.
72 if (TWIInfo.mode == RepeatedStartSent)
73 {
74 TWIInfo.mode = Initializing;
75 TWDR = TWITransmitBuffer[TXBuffIndex++]; // Load data to transmit buffer
76 TWISendTransmit(); // Send the data
77 }
78 else // Otherwise, just send the normal start signal to begin transmission.
79 {
80 TWIInfo.mode = Initializing;
81 TWISendStart();
82 }
83 if(blocking){
84 // Wait until ready
85 while (!isTWIReady()){_delay_us(1);}
86 }
87}
88
89
90// uint8_t TWITransmitData(void *const TXdata, uint8_t dataLen, uint8_t repStart)
91// {
92// if (dataLen <= TXMAXBUFLEN)
93// {
94// // Wait until ready
95// while (!isTWIReady()) {_delay_us(1);}
96// // Set repeated start mode
97// TWIInfo.repStart = repStart;
98// // Copy data into the transmit buffer
99// uint8_t *data = (uint8_t *)TXdata;
100// for (int i = 0; i < dataLen; i++)
101// {
102// TWITransmitBuffer[i] = data[i];
103// }
104// // Copy transmit info to global variables
105// TXBuffLen = dataLen;
106// TXBuffIndex = 0;
107
108// // If a repeated start has been sent, then devices are already listening for an address
109// // and another start does not need to be sent.
110// if (TWIInfo.mode == RepeatedStartSent)
111// {
112// TWIInfo.mode = Initializing;
113// TWDR = TWITransmitBuffer[TXBuffIndex++]; // Load data to transmit buffer
114// TWISendTransmit(); // Send the data
115// }
116// else // Otherwise, just send the normal start signal to begin transmission.
117// {
118// TWIInfo.mode = Initializing;
119// TWISendStart();
120// }
121
122// }
123// else
124// {
125// return 1; // return an error if data length is longer than buffer
126// }
127// return 0;
128// }
129
130uint8_t TWIReadData(uint8_t TWIaddr, uint8_t bytesToRead, uint8_t repStart)
131{
132 // Check if number of bytes to read can fit in the RXbuffer
133 if (bytesToRead < RXMAXBUFLEN)
134 {
135 // Reset buffer index and set RXBuffLen to the number of bytes to read
136 RXBuffIndex = 0;
137 RXBuffLen = bytesToRead;
138 // Create the one value array for the address to be transmitted
139 uint8_t TXdata[1];
140 // Shift the address and AND a 1 into the read write bit (set to write mode)
141 TXdata[0] = (TWIaddr << 1) | 0x01;
142 // Use the TWITransmitData function to initialize the transfer and address the slave
143 TWITransmitData(TXdata, 1, repStart, 0);
144 }
145 else
146 {
147 return 0;
148 }
149 return 1;
150}
151
152ISR (TWI_vect)
153{
154 switch (TWI_STATUS)
155 {
156 // ----\/ ---- MASTER TRANSMITTER OR WRITING ADDRESS ----\/ ---- //
157 case TWI_MT_SLAW_ACK: // SLA+W transmitted and ACK received
158 // Set mode to Master Transmitter
159 TWIInfo.mode = MasterTransmitter;
160 case TWI_START_SENT: // Start condition has been transmitted
161 case TWI_MT_DATA_ACK: // Data byte has been transmitted, ACK received
162 if (TXBuffIndex < TXBuffLen) // If there is more data to send
163 {
164 TWDR = TWITransmitBuffer[TXBuffIndex++]; // Load data to transmit buffer
165 TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
166 TWISendTransmit(); // Send the data
167 }
168 // This transmission is complete however do not release bus yet
169 else if (TWIInfo.repStart)
170 {
171 TWIInfo.errorCode = 0xFF;
172 TWISendStart();
173 }
174 // All transmissions are complete, exit
175 else
176 {
177 TWIInfo.mode = Ready;
178 TWIInfo.errorCode = 0xFF;
179 TWISendStop();
180 }
181 break;
182
183 // ----\/ ---- MASTER RECEIVER ----\/ ---- //
184
185 case TWI_MR_SLAR_ACK: // SLA+R has been transmitted, ACK has been received
186 // Switch to Master Receiver mode
187 TWIInfo.mode = MasterReceiver;
188 // If there is more than one byte to be read, receive data byte and return an ACK
189 if (RXBuffIndex < RXBuffLen-1)
190 {
191 TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
192 TWISendACK();
193 }
194 // Otherwise when a data byte (the only data byte) is received, return NACK
195 else
196 {
197 TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
198 TWISendNACK();
199 }
200 break;
201
202 case TWI_MR_DATA_ACK: // Data has been received, ACK has been transmitted.
203
204 /// -- HANDLE DATA BYTE --- ///
205 TWIReceiveBuffer[RXBuffIndex++] = TWDR;
206 // If there is more than one byte to be read, receive data byte and return an ACK
207 if (RXBuffIndex < RXBuffLen-1)
208 {
209 TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
210 TWISendACK();
211 }
212 // Otherwise when a data byte (the only data byte) is received, return NACK
213 else
214 {
215 TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
216 TWISendNACK();
217 }
218 break;
219
220 case TWI_MR_DATA_NACK: // Data byte has been received, NACK has been transmitted. End of transmission.
221
222 /// -- HANDLE DATA BYTE --- ///
223 TWIReceiveBuffer[RXBuffIndex++] = TWDR;
224 // This transmission is complete however do not release bus yet
225 if (TWIInfo.repStart)
226 {
227 TWIInfo.errorCode = 0xFF;
228 TWISendStart();
229 }
230 // All transmissions are complete, exit
231 else
232 {
233 TWIInfo.mode = Ready;
234 TWIInfo.errorCode = 0xFF;
235 TWISendStop();
236 }
237 break;
238
239 // ----\/ ---- MT and MR common ----\/ ---- //
240
241 case TWI_MR_SLAR_NACK: // SLA+R transmitted, NACK received
242 case TWI_MT_SLAW_NACK: // SLA+W transmitted, NACK received
243 case TWI_MT_DATA_NACK: // Data byte has been transmitted, NACK received
244 case TWI_LOST_ARBIT: // Arbitration has been lost
245 // Return error and send stop and set mode to ready
246 if (TWIInfo.repStart)
247 {
248 TWIInfo.errorCode = TWI_STATUS;
249 TWISendStart();
250 }
251 // All transmissions are complete, exit
252 else
253 {
254 TWIInfo.mode = Ready;
255 TWIInfo.errorCode = TWI_STATUS;
256 TWISendStop();
257 }
258 break;
259 case TWI_REP_START_SENT: // Repeated start has been transmitted
260 // Set the mode but DO NOT clear TWINT as the next data is not yet ready
261 TWIInfo.mode = RepeatedStartSent;
262 break;
263
264 // ----\/ ---- SLAVE RECEIVER ----\/ ---- //
265
266 // TODO IMPLEMENT SLAVE RECEIVER FUNCTIONALITY
267
268 // ----\/ ---- SLAVE TRANSMITTER ----\/ ---- //
269
270 // TODO IMPLEMENT SLAVE TRANSMITTER FUNCTIONALITY
271
272 // ----\/ ---- MISCELLANEOUS STATES ----\/ ---- //
273 case TWI_NO_RELEVANT_INFO: // It is not really possible to get into this ISR on this condition
274 // Rather, it is there to be manually set between operations
275 break;
276 case TWI_ILLEGAL_START_STOP: // Illegal START/STOP, abort and return error
277 TWIInfo.errorCode = TWI_ILLEGAL_START_STOP;
278 TWIInfo.mode = Ready;
279 TWISendStop();
280 break;
281 }
282
283}
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