Diff: lcd_i2c.cpp

Revision:

0:a4d44dfd2f03

--- /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);
+}
+
+
+