Gary Richardson
Test of LCD code
Revision 0:a4d44dfd2f03, committed 2014-05-30
- Comitter:
- garyr
- Date:
- Fri May 30 12:24:56 2014 +0000
- Commit message:
- LCD test code
Changed in this revision
diff -r 000000000000 -r a4d44dfd2f03 lcd_i2c.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/lcd_i2c.cpp Fri May 30 12:24:56 2014 +0000
@@ -0,0 +1,148 @@
+#include "mbed.h"
+#include "lcd_i2c.h"
+/*
+ LCD (Optrex DCM16230, DCM20261, etc.) via I2C using a PCF8574
+
+ Frequency (clks/sec) Frequency
+ Transfer rate = ------------------------------------------------ = ---------------- (characters/sec)
+ 9 clks/write * 3 writes/nibble * 2 nibbles/character 54
+*/
+I2C i2c(p9, p10); // (sda, scl)
+Serial pc2(USBTX, USBRX); // tx, rx
+
+// PCF8574 output bits Px
+#define RS BIT1
+#define RW BIT2
+#define E BIT3
+#define DB4 BIT4
+#define DB5 BIT5
+#define DB6 BIT6
+#define DB7 BIT7
+
+char update[NUPDATE];
+char cw, address;
+
+int updateDisplay(char *str, int nchars)
+{
+char w, ch, *p;
+int n, k, rc;
+
+ if (nchars > 20)
+ return 1;
+ n = 0;
+ p = update;
+ for (k = 0; k < nchars; k++)
+ {
+ // write most significant nibble
+ ch = *str++;
+ w = (ch & 0xf0) | cw;
+ *p++ = w;
+ *p++ = w | E;
+ *p++ = w;
+
+ // write least significant nibble
+ w = (ch << 4) | cw;
+ *p++ = w;
+ *p++ = w | E;
+ *p++ = w;
+ n += 6;
+ }
+ rc = i2c.write(address, update, n); // rc == 0 ==> ACK
+ return rc;
+}
+
+int write4Bits(char data)
+{
+char w;
+int rc;
+
+ w = (data & 0xf0) | cw; // grab the left nibble
+ update[0] = w;
+ update[1] = w | E;
+ update[2] = w & ~ E;
+ rc = i2c.write(address, update, 3);
+ return rc;
+}
+
+int initLcd(int i2cAddress, int frequency)
+{
+typedef struct {
+ char cmd;
+ char numNibbles;
+ char delayMs;
+ //char testBF;
+} INIT;
+static const INIT initData[] = {
+ {3, 1, 5},
+ {3, 1, 1},
+ {3, 1, 1},
+ {2, 1, 1}, // Function set: 4-bit interface
+ {0x28, 2, 2}, // Function set: 2 lines, 5x7
+ {0x08, 2, 2}, // Display off
+ {0x01, 2, 16}, // Clear display
+ {0x06, 2, 2}, // Entry mode set: No increment, shift cursor
+ {0x0e, 2, 2}}; // Display on: cursor on, blink off
+#define NINITD (sizeof(initData)/sizeof(initData[0]))
+INIT *p;
+int k, rc;
+ // Initialization must start at least 16 ms after power up.
+ i2c.frequency(frequency);
+ address = i2cAddress;
+ cw = 0;
+ p = (INIT *)initData;
+ for (k = 0; k < NINITD; k++)
+ {
+ //p = (INIT *)&initData[k];
+ if (p->numNibbles == 1)
+ rc = write4Bits(p->cmd << 4);
+ else
+ {
+ rc = write4Bits(p->cmd); // output the most significant nibble
+ wait_us(10); // this will need to be adjusted when printf stmts are removed
+ rc |= write4Bits(p->cmd << 4); // output the least significant nibble
+ }
+ if (rc)
+ break;
+ wait_ms(p->delayMs);
+ p++;
+ }
+ return rc;
+}
+
+int lcdWriteMsg(char *msg)
+{ // msg must be a null-terminated string
+char rc;
+ cw |= RS; // data
+ cw &= ~RW; // write
+ rc = updateDisplay(msg, strlen(msg));
+ return rc;
+}
+
+int lcdWriteCmd(char cmd, int delayMs)
+{
+int rc;
+ cw &= ~RS; // command
+ rc = write4Bits(cmd);
+ wait_us(10);
+ rc |= write4Bits(cmd << 4);
+ if (delayMs)
+ wait_ms(delayMs);
+ return rc;
+}
+
+int lcdPositionCursor(char row, char col)
+{
+// Code may not be correct for displays larger than 20 x 2
+int x, rc;
+ x = 0x80 | ((row & 1)<<6) | (col & 0xf);
+ rc = lcdWriteCmd(x, 1);
+ return rc;
+}
+
+int lcdClearDisplay(void)
+{
+ return lcdWriteCmd(1, 16);
+}
+
+
+
diff -r 000000000000 -r a4d44dfd2f03 lcd_i2c.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/lcd_i2c.h Fri May 30 12:24:56 2014 +0000 @@ -0,0 +1,22 @@ +#ifndef H_LCD_I2C +#define H_LCD_I2C + +#define BIT0 1 +#define BIT1 2 +#define BIT2 4 +#define BIT3 8 +#define BIT4 0x10 +#define BIT5 0x20 +#define BIT6 0x40 +#define BIT7 0x80 + +#define DISPLAY_WIDTH 20 +#define DISPLAY_NUMROWS 2 +#define NUPDATE (DISPLAY_WIDTH*6) + +extern int initLcd(int i2cAddress, int frequency); +extern int lcdWriteMsg(char *msg); +extern int lcdClearDisplay(void); +extern int lcdPositionCursor(char row, char col); + +#endif
diff -r 000000000000 -r a4d44dfd2f03 main.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Fri May 30 12:24:56 2014 +0000
@@ -0,0 +1,62 @@
+#include "mbed.h"
+#include "lcd_i2c.h"
+
+Serial pc(USBTX, USBRX); // tx, rx
+extern char update[NUPDATE];
+
+int main() {
+char ch, row, col;
+int address, frequency, rc;
+
+ row = col = 0;
+ pc.printf("Enter address ");
+ pc.scanf("%x", &address);
+ pc.printf("\n\rEnter frequency ");
+ pc.scanf("%d", &frequency);
+ pc.printf("\n\raddress: 0x%x frequency=%d\n\r", address, frequency);
+ while(1)
+ {
+ pc.scanf("%c ", &ch);
+ if (ch == 27)
+ break;
+ pc.printf("%c", ch);
+ switch (ch)
+ {
+ case 'c':
+ rc = initLcd(address, frequency);
+ pc.printf("rc: %d ", rc);
+ row = 0;
+ col = 0;
+ break;
+ case 'd':
+ rc = lcdWriteMsg("Now is the time");
+ pc.printf("rc: %d ", rc);
+ break;
+ case 'e':
+ rc = lcdPositionCursor(row, col);
+ pc.printf("rc: %d ", rc);
+ row ^= 1;
+ col = (col + 1) % 20;
+ break;
+ case 'f':
+ rc = lcdClearDisplay();
+ pc.printf("rc: %d ", rc);
+ break;
+ case 'g':
+ {
+ int k, j;
+ j = 0;
+ pc.printf("\n\r");
+ for (k = 0; k < 6; k++)
+ {
+ pc.printf("%02x %02x %02x\n\r", update[j], update[j+1], update[j+2]);
+ j += 3;
+ }
+ }
+ break;
+ default:
+ break;
+ }
+ }
+ pc.printf("done\n\r");
+}
diff -r 000000000000 -r a4d44dfd2f03 mbed.bld --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Fri May 30 12:24:56 2014 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/6473597d706e \ No newline at end of file