Explanation:
This program demonstrates how to read and write data from an EEPROM device using the serial protocal called I2C.
This program uses the hardware I2C module within the microcontroller. If your microcontroller does not have a hardware I2C module then please use the software I2C GCBASIC ibrary.
This program has three sections.
- Read a single byte from the EEPROM
- Write and read a page of 64 bytes to and from the EEPROM, and
- Finally display the contents of the EEPROM.
This program has an interrupt driven serial handler to capture and manage input from a serial terminal.
Demonstration program:
'Change the microcontroller, frequency and config to suit your needs.
#chip 16F1937, 32
#config MCLRE_ON
'Required Library to read and write to an EEPROM
#include <I2CEEPROM.h>
' Define I2C settings - CHANGE PORTS
#define HI2C_BAUD_RATE 400
#define HI2C_DATA PORTC.4
#define HI2C_CLOCK PORTC.3
'I2C pins need to be input for SSP module for Microchip PIC devices.
Dir HI2C_DATA in
Dir HI2C_CLOCK in
'I2C MASTER MODE
HI2CMode Master
' THIS CONFIG OF THE SERIAL PORT WORKS WITH max232 THEN TO PC
' USART settings
#define USART_BAUD_RATE 9600
Dir PORTc.6 Out
Dir PORTc.7 In
#define USART_DELAY OFF
#define USART_TX_BLOCKING
wait 500 ms
'Create a Serial Interrupt Handler
On Interrupt UsartRX1Ready Call readUSART
' Constants etc required for the serial Buffer Ring
#define BUFFER_SIZE 32
#define bkbhit (next_in <> next_out)
' Required Variables for the serial Buffer Ring
Dim buffer(BUFFER_SIZE)
Dim next_in as byte: next_in = 1
Dim next_out as byte: next_out = 1
Dim syncbyte as Byte
wait 125 ms
' Read ONE byte from the EEPROM
dim DeviceID as byte
dim EepromAddress, syscounter as word
#define EEpromDevice 0xA0
'Master Main Loop
location = 0
'Define our array
dim outarray(64), inarray(64)
do
HSerPrintCRLF 2
HSerPrint "Commence Array Write and Read"
'Populate the array
for tt = 1 to 64
outarray(tt) = tt
next
'Library write call is: eeprom_wr_array(device_number, page_size, address, array_name, number_of_bytes)
eeprom_wr_array(EEpromDevice, 64, location, outarray, 64)
'Library read call is: eeprom_rd_array(device_number, address, array_name, number_of_bytes)
eeprom_rd_array(EEpromDevice, location, inarray, 64)
'Show results of the read of the I2C EEPROM
HSerPrintCRLF 2
for tt = 1 to 64
if outarray(tt) <> inarray(tt) then
Hserprint "!"
HSerPrint inarray(tt)
else
HSerPrint inarray(tt)
end if
HSerPrint ","
next
HSerPrintCRLF 2
HSerPrint "Commence Write and Read a single byte":HSerPrintCRLF
HSerPrint "Read value should be "
HSerPrint str(location):HSerPrintCRLF
HSerPrint "Read = "
'Use library to write and read from the I2C EEPROM
eeprom_wr_byte (EEpromDevice, location, location)
eeprom_rd_byte (EEpromDevice, location, bbyte )
HSerPrint bbyte
location++
HSerPrintCRLF 2
'Show the connnected I2C devices on the Serial terminal.
HI2CDeviceSearch
HSerPrint "Commence Dump of the EEPROM"
validateEEPROM
Loop
End
'Show the attached I2C devices
sub HI2CDeviceSearch
'Assumes serial is operational
HSerPrintCRLF
HSerPrint "I2C Device Search"
HSerPrintCRLF 2
for deviceID = 0 to 255
HI2CStart
HI2CSend ( deviceID )
if HI2CAckPollState = false then
HSerPrint "ID: 0x"
HSerPrint hex(deviceID)
HSerSend 9
testid = deviceID | 1
select case testid
case 49
Hserprint "DS2482_1Channel_1Wire Master"
case 65
Hserprint "Serial_Expander_Device"
Case 73
Hserprint "Serial_Expander_Device"
case 161
Hserprint "EEProm_Device_Device"
case 163
Hserprint "EEProm_Device_Device"
case 165
Hserprint "EEProm_Device_Device"
case 167
Hserprint "EEProm_Device_Device"
case 169
Hserprint "EEProm_Device_Device"
case 171
Hserprint "EEProm_Device_Device"
case 173
Hserprint "EEProm_Device_Device"
case 175
Hserprint "EEProm_Device_Device"
case 209
Hserprint "DS1307_RTC_Device"
case 249
Hserprint "FRAM_Device"
case else
Hserprint "Unknown_Device"
end select
HI2CSend ( 0 )
HSerPrintCRLF
end if
HI2CStop
next
HSerPrint "End of Device Search"
HSerPrintCRLF 2
end sub
'Validation EEPROOM code
sub validateEEPROM
EepromAddress = 0
HSerPrintCRLF 2
HSerPrint "Hx"
HSerPrint hex(EepromAddress_h)
HSerPrint hex(EepromAddress)
HSerPrint " "
for EepromAddress = 0 to 0xffff
'Read from EEPROM using a library function
eeprom_rd_byte EEPromDevice, EepromAddress, objType
HSerPrint hex(objType)+" "
if ((EepromAddress+1) % 8 ) = 0 then
HSerPrintCRLF
HSerPrint "Hx"
syscounter = EepromAddress + 1
HSerPrint hex(syscounter_h)
HSerPrint hex(syscounter)
HSerPrint " "
end if
'Has serial data been received
if bkbhit then
syschar = bgetc
select case syschar
case 32
do while bgetc = 32
loop
case else
HSerPrintCRLF
HSerPrint "Done"
exit sub
end select
end if
next
HSerPrintCRLF
HSerPrint "Done"
end Sub
' Start of Serial Support functions
' Required to read the serial port
' Assumes serial port has been initialised
Sub readUSART
buffer(next_in) = HSerReceive
temppnt = next_in
next_in = ( next_in + 1 ) % BUFFER_SIZE
if ( next_in = next_out ) then ' buffer is full!!
next_in = temppnt
end if
End Sub
' Serial Support functions
' Get characters from the serial port
function bgetc
wait while !(bkbhit)
bgetc = buffer(next_out)
next_out=(next_out+1) % BUFFER_SIZE
end Function