REVELTRONICS

DS28EC20 is 1-wire device with 20kB EEPROM (80 pages x 32 bytes = 2560 bytes) with additional registers:
- Protection Control Blocks (10 bytes) read/(write)*
- User EEPROM (20 bytes) read/write
- Memory Block Lock (1 byte) read/(write)*
- Register Page Lock (1 byte) read/(write)*
- Factory Byte (1 byte) read only
- Manufacturer ID (2 bytes) read only
- 64-bit ID read only
* for factory new device these registers are read/write, but when you program to it 0x55 (write protection) or 0xAA (EPROM mode) you can not change it anymore and it becomes read only.

Please take a look at memory organization from DS28EC20 datasheet page9.

READ/WRITE Data Memory area

You can reprogramm Data Memory of DS28EC20 (block 0-9 = pages 0-79 = 2560 bytes of data) with REVELPROG-IS (since v1.8.5) by selecting device from memory database EEPROM -> 1-Wire -> Maxim -> DS28EC20 and use standard read/write buttons from application. It's simple, nothing to explain

READ/WRITE additional registers

You can also use Custom Script Tool to change Protection Registers or User Memory.

In this tutorial I'll show example scripts how to read and write above registers.


READ additional registers

Protection Control Blocks (0-9) are located from address 0x0A00 to address 0xA09h. You can read them using below scripts:

By default all bytes are equal to zeros (no protection). 55h in any byte means that according block is write protected. AAh means that according block is in EPROM emulation mode.

User EEPROM (20 bytes) starts from address 0x0A0A and ends at 0x0A1D. It can be read by using below script:


At address 0x0A1E is located Memory Block Lock (it blocks copy-scratchpad function) and at address 0x0A1F is located Register Page Lock (write protection for protection control blocks). At address 0x0A23-0x0A24 (2 bytes) is manufacturer ID and it's read only (you can order DS28EC20 from Maxim with required manufacturer ID) and at address 0x0A20 is control byte for manufacturer ID (0x55 means no valid manufactruer ID, 0xAAh means valid manufacturer ID). You can read all these bytes using custom script tool too:


WRITE additional registers (be careful!)

Factory new chip have registers in factory reset state. You can change block protection or configure EPROM emulation mode for selected blocks. But be careful, once changed it becomes read-only! Datasheet says "Once programmed to AAh or 55h this address becomes read only. All other codes can be stored, but neither write protect the address nor activate any function" so be careful. Writing procedure is described in datasheet pages 12-15 - you have flow diagram which I used to prepare you writing scripts (please read my notes below before using it):


In first step we are writing scratchpad. It's additional buffer between RAM and EEPROM. Changing scratchpad only is safe. In DATA field you have total 32 bytes: first 10 bytes are protection control bytes (writing 0x55 or 0xAA to any of these bytes will protect selected block or configure it in EPROM emulation mode), next 20 bytes is user EEPROM, and next 2 bytes is memory block lock and register page lock. In total there are 32 bytes - in script above all are equal to default state (zeros) but you can change it according to your needs.

Second step is required to read authorization code (without this code we can not change registers). So we are reading address bytes (TA1 and TA2) + authorization code (ES) + 32 bytes which you provided in first step.

You can safely run script with step 1 and step 2 (without step 3) - it will not change registers. It should read 35 bytes. 3rd byte is authorization code - please write it down, it will be required for writing. In example above authorization code is 0x1F but in your case it may be different (it depends on data bytes in step 1)

Third step is copy scratchpad operation. You need to provide authorization code here (0x1F in this example - replace it with your own - you can read it in step 2). It copies scratchpad (from step 1) to device memory. Valid authorization code (which you can read in step 2) is required for operation success.

When you run above script (3 operations: step 1 + step 2 + step 3 with valid authorization code) registers will be reprogrammed.

That's all Hope it helps!