Diff: main.cpp

Revision:

0:34c4fa6b49ac

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Jul 20 10:43:06 2016 +0000
@@ -0,0 +1,100 @@
+// NOTES:
+// 1. mbed.h MUST BE the revision from 30 Mar 2016, otherwise it will behave strange and unexpected! Older or newer versions won't work.
+//    For example, with the latest version of mbed.h from 25 May 2016, the "wait" function does not work at all, it's the same as if it's not there.
+// 2. writeEEPROM has 64 bytes limitation. If you want to write more at once, read http://www.hobbytronics.co.uk/eeprom-page-write how this guy made it work.
+//    Im not interested in storing data above 64 bytes (1 page). The 24LC256 chip has 4096 pages.
+// 3. reading the entire eeprom does its job until the 512 byte, then it will cycle from zero. I don't know why...
+#include "mbed.h"
+
+// function declaration
+void writeEEPROM(int address, unsigned int eeaddress, char *data, int size);
+void readEEPROM(int address, unsigned int eeaddress, char *data, int size);
+
+// classes and functions instantiation
+I2C i2c(I2C_SDA, I2C_SCL);
+Serial pc(SERIAL_TX, SERIAL_RX);
+
+// settings
+int address = 0xA8; // in my case A2 = high, A1 = low, A0 = low, so the address is 1010 1000 = A8 (format 1 0 1 0 A3 A2 A1 R/W)
+
+int main()
+{
+    pc.printf("24LC256 I2C EEPROM started...\n");
+
+    int pointerAdddress = 0;
+
+    // write some data on eeprom
+    char writeData[] = {"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec f"}; // the text length must be below 64 bytes
+    char writeDataLen = 0;
+    do {writeDataLen++;} while (writeData[writeDataLen]); // calculate the text length
+    /*
+    writeEEPROM(address, pointerAdddress, writeData, writeDataLen);
+
+    pc.printf("Data written: %s\n", writeData);
+    */
+
+    // read the data back
+    char data_read[writeDataLen];
+    readEEPROM(address, pointerAdddress, data_read, writeDataLen);
+
+    pc.printf("Data read: %s\n", data_read);
+
+    // read the entire eeprom
+    /*
+    pc.printf("Printing the entire EEPROM array (64 columns, 4096 rows):\n");
+    int i;
+    char data_chunk[64];
+    int pointer;
+    for (i = 0; i < 4096; i++)
+    {
+        pointer = 64 * i;
+        readEEPROM(address, pointer, data_chunk, 64);
+        pc.printf("row: %4d, data: %s\n", i, data_chunk);
+    }
+    */
+
+    // delete the entire eeprom
+    /*
+    pc.printf("Deleting the entire EEPROM array (64 columns, 4096 rows):\n");
+    int i;
+    int pointer;
+    char deleteData[] = {"0000000000000000000000000000000000000000000000000000000000000000"}; // 64 bytes data length of zeros
+    for (i = 0; i < 4096; i++)
+    {
+        pointer = 64 * i;
+        writeEEPROM(address, pointer, deleteData, 64);
+    }
+    pc.printf("Erasing complete\n");
+    */
+}
+
+// this function has 63 bytes write limit
+void writeEEPROM(int address, unsigned int eeaddress, char *data, int size)
+{
+    char i2cBuffer[size + 2];
+    i2cBuffer[0] = (unsigned char)(eeaddress >> 8); // MSB
+    i2cBuffer[1] = (unsigned char)(eeaddress & 0xFF); // LSB
+
+    for (int i = 0; i < size; i++) {
+        i2cBuffer[i + 2] = data[i];
+    }
+
+    int result = i2c.write(address, i2cBuffer, size + 2, false);
+    wait_ms(6);
+}
+
+// this function has no read limit
+void readEEPROM(int address, unsigned int eeaddress, char *data, int size)
+{
+    char i2cBuffer[2];
+    i2cBuffer[0] = (unsigned char)(eeaddress >> 8); // MSB
+    i2cBuffer[1] = (unsigned char)(eeaddress & 0xFF); // LSB
+
+    // Reset eeprom pointer address
+    int result = i2c.write(address, i2cBuffer, 2, false);
+    wait_ms(6);
+
+    // Read eeprom
+    i2c.read(address, data, size);
+    wait_ms(6);
+}
\ No newline at end of file