Gary Richardson
/
testLCD
Test of LCD code
lcd_i2c.cpp@0:a4d44dfd2f03, 2014-05-30 (annotated)
- Committer:
- garyr
- Date:
- Fri May 30 12:24:56 2014 +0000
- Revision:
- 0:a4d44dfd2f03
LCD test code
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
garyr | 0:a4d44dfd2f03 | 1 | #include "mbed.h" |
garyr | 0:a4d44dfd2f03 | 2 | #include "lcd_i2c.h" |
garyr | 0:a4d44dfd2f03 | 3 | /* |
garyr | 0:a4d44dfd2f03 | 4 | LCD (Optrex DCM16230, DCM20261, etc.) via I2C using a PCF8574 |
garyr | 0:a4d44dfd2f03 | 5 | |
garyr | 0:a4d44dfd2f03 | 6 | Frequency (clks/sec) Frequency |
garyr | 0:a4d44dfd2f03 | 7 | Transfer rate = ------------------------------------------------ = ---------------- (characters/sec) |
garyr | 0:a4d44dfd2f03 | 8 | 9 clks/write * 3 writes/nibble * 2 nibbles/character 54 |
garyr | 0:a4d44dfd2f03 | 9 | */ |
garyr | 0:a4d44dfd2f03 | 10 | I2C i2c(p9, p10); // (sda, scl) |
garyr | 0:a4d44dfd2f03 | 11 | Serial pc2(USBTX, USBRX); // tx, rx |
garyr | 0:a4d44dfd2f03 | 12 | |
garyr | 0:a4d44dfd2f03 | 13 | // PCF8574 output bits Px |
garyr | 0:a4d44dfd2f03 | 14 | #define RS BIT1 |
garyr | 0:a4d44dfd2f03 | 15 | #define RW BIT2 |
garyr | 0:a4d44dfd2f03 | 16 | #define E BIT3 |
garyr | 0:a4d44dfd2f03 | 17 | #define DB4 BIT4 |
garyr | 0:a4d44dfd2f03 | 18 | #define DB5 BIT5 |
garyr | 0:a4d44dfd2f03 | 19 | #define DB6 BIT6 |
garyr | 0:a4d44dfd2f03 | 20 | #define DB7 BIT7 |
garyr | 0:a4d44dfd2f03 | 21 | |
garyr | 0:a4d44dfd2f03 | 22 | char update[NUPDATE]; |
garyr | 0:a4d44dfd2f03 | 23 | char cw, address; |
garyr | 0:a4d44dfd2f03 | 24 | |
garyr | 0:a4d44dfd2f03 | 25 | int updateDisplay(char *str, int nchars) |
garyr | 0:a4d44dfd2f03 | 26 | { |
garyr | 0:a4d44dfd2f03 | 27 | char w, ch, *p; |
garyr | 0:a4d44dfd2f03 | 28 | int n, k, rc; |
garyr | 0:a4d44dfd2f03 | 29 | |
garyr | 0:a4d44dfd2f03 | 30 | if (nchars > 20) |
garyr | 0:a4d44dfd2f03 | 31 | return 1; |
garyr | 0:a4d44dfd2f03 | 32 | n = 0; |
garyr | 0:a4d44dfd2f03 | 33 | p = update; |
garyr | 0:a4d44dfd2f03 | 34 | for (k = 0; k < nchars; k++) |
garyr | 0:a4d44dfd2f03 | 35 | { |
garyr | 0:a4d44dfd2f03 | 36 | // write most significant nibble |
garyr | 0:a4d44dfd2f03 | 37 | ch = *str++; |
garyr | 0:a4d44dfd2f03 | 38 | w = (ch & 0xf0) | cw; |
garyr | 0:a4d44dfd2f03 | 39 | *p++ = w; |
garyr | 0:a4d44dfd2f03 | 40 | *p++ = w | E; |
garyr | 0:a4d44dfd2f03 | 41 | *p++ = w; |
garyr | 0:a4d44dfd2f03 | 42 | |
garyr | 0:a4d44dfd2f03 | 43 | // write least significant nibble |
garyr | 0:a4d44dfd2f03 | 44 | w = (ch << 4) | cw; |
garyr | 0:a4d44dfd2f03 | 45 | *p++ = w; |
garyr | 0:a4d44dfd2f03 | 46 | *p++ = w | E; |
garyr | 0:a4d44dfd2f03 | 47 | *p++ = w; |
garyr | 0:a4d44dfd2f03 | 48 | n += 6; |
garyr | 0:a4d44dfd2f03 | 49 | } |
garyr | 0:a4d44dfd2f03 | 50 | rc = i2c.write(address, update, n); // rc == 0 ==> ACK |
garyr | 0:a4d44dfd2f03 | 51 | return rc; |
garyr | 0:a4d44dfd2f03 | 52 | } |
garyr | 0:a4d44dfd2f03 | 53 | |
garyr | 0:a4d44dfd2f03 | 54 | int write4Bits(char data) |
garyr | 0:a4d44dfd2f03 | 55 | { |
garyr | 0:a4d44dfd2f03 | 56 | char w; |
garyr | 0:a4d44dfd2f03 | 57 | int rc; |
garyr | 0:a4d44dfd2f03 | 58 | |
garyr | 0:a4d44dfd2f03 | 59 | w = (data & 0xf0) | cw; // grab the left nibble |
garyr | 0:a4d44dfd2f03 | 60 | update[0] = w; |
garyr | 0:a4d44dfd2f03 | 61 | update[1] = w | E; |
garyr | 0:a4d44dfd2f03 | 62 | update[2] = w & ~ E; |
garyr | 0:a4d44dfd2f03 | 63 | rc = i2c.write(address, update, 3); |
garyr | 0:a4d44dfd2f03 | 64 | return rc; |
garyr | 0:a4d44dfd2f03 | 65 | } |
garyr | 0:a4d44dfd2f03 | 66 | |
garyr | 0:a4d44dfd2f03 | 67 | int initLcd(int i2cAddress, int frequency) |
garyr | 0:a4d44dfd2f03 | 68 | { |
garyr | 0:a4d44dfd2f03 | 69 | typedef struct { |
garyr | 0:a4d44dfd2f03 | 70 | char cmd; |
garyr | 0:a4d44dfd2f03 | 71 | char numNibbles; |
garyr | 0:a4d44dfd2f03 | 72 | char delayMs; |
garyr | 0:a4d44dfd2f03 | 73 | //char testBF; |
garyr | 0:a4d44dfd2f03 | 74 | } INIT; |
garyr | 0:a4d44dfd2f03 | 75 | static const INIT initData[] = { |
garyr | 0:a4d44dfd2f03 | 76 | {3, 1, 5}, |
garyr | 0:a4d44dfd2f03 | 77 | {3, 1, 1}, |
garyr | 0:a4d44dfd2f03 | 78 | {3, 1, 1}, |
garyr | 0:a4d44dfd2f03 | 79 | {2, 1, 1}, // Function set: 4-bit interface |
garyr | 0:a4d44dfd2f03 | 80 | {0x28, 2, 2}, // Function set: 2 lines, 5x7 |
garyr | 0:a4d44dfd2f03 | 81 | {0x08, 2, 2}, // Display off |
garyr | 0:a4d44dfd2f03 | 82 | {0x01, 2, 16}, // Clear display |
garyr | 0:a4d44dfd2f03 | 83 | {0x06, 2, 2}, // Entry mode set: No increment, shift cursor |
garyr | 0:a4d44dfd2f03 | 84 | {0x0e, 2, 2}}; // Display on: cursor on, blink off |
garyr | 0:a4d44dfd2f03 | 85 | #define NINITD (sizeof(initData)/sizeof(initData[0])) |
garyr | 0:a4d44dfd2f03 | 86 | INIT *p; |
garyr | 0:a4d44dfd2f03 | 87 | int k, rc; |
garyr | 0:a4d44dfd2f03 | 88 | // Initialization must start at least 16 ms after power up. |
garyr | 0:a4d44dfd2f03 | 89 | i2c.frequency(frequency); |
garyr | 0:a4d44dfd2f03 | 90 | address = i2cAddress; |
garyr | 0:a4d44dfd2f03 | 91 | cw = 0; |
garyr | 0:a4d44dfd2f03 | 92 | p = (INIT *)initData; |
garyr | 0:a4d44dfd2f03 | 93 | for (k = 0; k < NINITD; k++) |
garyr | 0:a4d44dfd2f03 | 94 | { |
garyr | 0:a4d44dfd2f03 | 95 | //p = (INIT *)&initData[k]; |
garyr | 0:a4d44dfd2f03 | 96 | if (p->numNibbles == 1) |
garyr | 0:a4d44dfd2f03 | 97 | rc = write4Bits(p->cmd << 4); |
garyr | 0:a4d44dfd2f03 | 98 | else |
garyr | 0:a4d44dfd2f03 | 99 | { |
garyr | 0:a4d44dfd2f03 | 100 | rc = write4Bits(p->cmd); // output the most significant nibble |
garyr | 0:a4d44dfd2f03 | 101 | wait_us(10); // this will need to be adjusted when printf stmts are removed |
garyr | 0:a4d44dfd2f03 | 102 | rc |= write4Bits(p->cmd << 4); // output the least significant nibble |
garyr | 0:a4d44dfd2f03 | 103 | } |
garyr | 0:a4d44dfd2f03 | 104 | if (rc) |
garyr | 0:a4d44dfd2f03 | 105 | break; |
garyr | 0:a4d44dfd2f03 | 106 | wait_ms(p->delayMs); |
garyr | 0:a4d44dfd2f03 | 107 | p++; |
garyr | 0:a4d44dfd2f03 | 108 | } |
garyr | 0:a4d44dfd2f03 | 109 | return rc; |
garyr | 0:a4d44dfd2f03 | 110 | } |
garyr | 0:a4d44dfd2f03 | 111 | |
garyr | 0:a4d44dfd2f03 | 112 | int lcdWriteMsg(char *msg) |
garyr | 0:a4d44dfd2f03 | 113 | { // msg must be a null-terminated string |
garyr | 0:a4d44dfd2f03 | 114 | char rc; |
garyr | 0:a4d44dfd2f03 | 115 | cw |= RS; // data |
garyr | 0:a4d44dfd2f03 | 116 | cw &= ~RW; // write |
garyr | 0:a4d44dfd2f03 | 117 | rc = updateDisplay(msg, strlen(msg)); |
garyr | 0:a4d44dfd2f03 | 118 | return rc; |
garyr | 0:a4d44dfd2f03 | 119 | } |
garyr | 0:a4d44dfd2f03 | 120 | |
garyr | 0:a4d44dfd2f03 | 121 | int lcdWriteCmd(char cmd, int delayMs) |
garyr | 0:a4d44dfd2f03 | 122 | { |
garyr | 0:a4d44dfd2f03 | 123 | int rc; |
garyr | 0:a4d44dfd2f03 | 124 | cw &= ~RS; // command |
garyr | 0:a4d44dfd2f03 | 125 | rc = write4Bits(cmd); |
garyr | 0:a4d44dfd2f03 | 126 | wait_us(10); |
garyr | 0:a4d44dfd2f03 | 127 | rc |= write4Bits(cmd << 4); |
garyr | 0:a4d44dfd2f03 | 128 | if (delayMs) |
garyr | 0:a4d44dfd2f03 | 129 | wait_ms(delayMs); |
garyr | 0:a4d44dfd2f03 | 130 | return rc; |
garyr | 0:a4d44dfd2f03 | 131 | } |
garyr | 0:a4d44dfd2f03 | 132 | |
garyr | 0:a4d44dfd2f03 | 133 | int lcdPositionCursor(char row, char col) |
garyr | 0:a4d44dfd2f03 | 134 | { |
garyr | 0:a4d44dfd2f03 | 135 | // Code may not be correct for displays larger than 20 x 2 |
garyr | 0:a4d44dfd2f03 | 136 | int x, rc; |
garyr | 0:a4d44dfd2f03 | 137 | x = 0x80 | ((row & 1)<<6) | (col & 0xf); |
garyr | 0:a4d44dfd2f03 | 138 | rc = lcdWriteCmd(x, 1); |
garyr | 0:a4d44dfd2f03 | 139 | return rc; |
garyr | 0:a4d44dfd2f03 | 140 | } |
garyr | 0:a4d44dfd2f03 | 141 | |
garyr | 0:a4d44dfd2f03 | 142 | int lcdClearDisplay(void) |
garyr | 0:a4d44dfd2f03 | 143 | { |
garyr | 0:a4d44dfd2f03 | 144 | return lcdWriteCmd(1, 16); |
garyr | 0:a4d44dfd2f03 | 145 | } |
garyr | 0:a4d44dfd2f03 | 146 | |
garyr | 0:a4d44dfd2f03 | 147 | |
garyr | 0:a4d44dfd2f03 | 148 |