Using Eeprom; Reading Value From Eeprom; Writing Value To Eeprom - Diamond Systems ELEKTRA FD-64 User Manual

16.2 Using EEPROM

There is an EEPROM used to store all TrimDAC adjustment values. These values are loaded on
reset or power-up, so it is critical that these values be correct in order to maintain accurate A/D
measurements. These settings are configured to defaults during manufacturing test – be sure
that you know what you are doing before changing these settings.
The EEPROM provides 256 bytes of non-volatile storage. The first 128 (addresses 00-0x7F)
bytes are reserved for Auto Calibration settings and should not be overwritten. The last 128 bytes
are available for user-accessible non-volatile storage.
Note that access to EEPROM data can be handled through the DSCUD software utilities.
Remember that bytes 0-127 are reserved for system use (TrimDAC autocal values); altering
those values will adversely affect system calibration.

16.2.1 READING VALUE FROM EEPROM

Example : read one byte from EEPROM location 128:
outp(base+3, 0x10);
outp(base+15, 0xA5); // unlock EEPROM
outp(base+13,0x80);
outp(base+14, 0xC0); // Initiate transfer, set to read
while (inp(base+14) & 0x20);
Data = inpb(base+12); // data returned from EEPROM access
outp(base+3, 0x0x00);
TrimDAC)
NOTE: This code does not take into consideration SCANEN and G0, G1 bits at base+3.

16.2.2 WRITING VALUE TO EEPROM

Example : write one byte (value = 0xaa) to EEPROM location 254, then verify the data:
outp(base+3, 0x10);
outp(base+15, 0xA5); // unlock EEPROM
outp(base+13,0xFE);
outp(base+12, 0xAA); // Set data to write to EEPROM
outp(base+14, 0x80); // Initiate transfer, set to write
while (inp(base+14) & 0x20);
outp(base+15, 0xA5); // unlock EEPROM
outp(base +13,0xFE); // set address location to 254 (0xFE)
outp(base+14, 0xC0); // Initiate transfer, set to read
while (inp(base+14) & 0x20);
Data = inpb(base+12); // data returned from EEPROM access; data should be 0xAA
outp(base+3, 0x00);
NOTE: This code does not take into consideration SCANEN and G0, G1 bits at base+3.
// set page to page 1
// set address location to 128 (0x80)
// Wait for EEPROM load to complete
// set page to page 0 (and re-enables lock on EEPROM /
// set page to page 1
// set address location to 254 (0xFE)
// Wait for EEPROM write to complete
// Wait for EEPROM load to complete
// set page to page 0 (and re-enables lock on EEPROM / TrimDAC)
Elektra CPU User Manual V1.00 Page 69