This project came to live because I found on aliexpress cheap clones of DS1990 that allow to change their ID ๐
Atmel Studio 7 with AVR-GCC toolchain 5.4.0
- Vcc: 5V
- MCU: ATMega32
- F_CPU: 16MHz
- IO:
- PD7: 1-Wire bus with 4,7k pullup
- PB0: LED 1 (H=led on , L=led off) - blink short when nothing is on 1W bus, long - when someting is on bus or commands are exec.
- PB1: LED 2 (H=led off, L=led off) - is on when RW1990 is programmed
- USART: 38400bps 8N1
The RW1990-test read is controlled via USART commands.
At CPU reset/Power on MCU sends to host PC via USART "hello" ๐
\r\n\r\nRW1990:START\r\n
(\r
- is CR character (carriage return) , \n
- is LF character (line feed))
Those commands are:
?
- send command list with few character description and 1wire lib versions
- scan 1-Wire bus for devicesr
- read 1st device on bus ROM IDn
- set new RW1990 ROM IDm
- print new RW1990 ROM IDw
- perform real write to RW1990 of new ROM ID
Each command is confirmed with only CR (ASCII: 0x0D = 13dec = Carriage return)
Not every one command will respond with itself. Whenever 1-W bus is accessed (1-Wire reset) there will be returned line with it's result in format:
1W:RESET=x
Where x is
- 0 = no 1-Wire slave(s) response to reset
- 1 = 1-Wire slave(s) responded to reset
Command ?
will not be explained - it's just too simple ๐
No parameters after command, will return lines:
1W:SCAN\r\n
and followed by 1W:RESET=x\r\n
. If rest is OK ("1") then all IDs of slave devices connected to bus will be printed in format (each device ID in separate line):
1W:SCAN:[scan_bit_mask_1byte]:[device_id_8bytes]:<OK/ER:CALC_CRC>\r\n
Where:
- scan_bit_mask_1byte - a 1 byte in HEX with bit mask for getting next device ID , if=0x00 then no more devices on bus
- device_id_8bytes - 8 bytes in HEX with device ID (family code, 6 bytes od unique ID (48bits) and CRC)
- <OK/ER:CALC_CRC> - if CRC is valid will be "OK", if not then will be "ER:" and followed by a byte in HEX with valid CRC
No parameters after command, will return lines:
1W:READ-ROM\r\n
and followed by 1W:RESET=x\r\n
. If rest is OK ("1") then 1st device on bus ID will be returned:
1W:READ-ROM:[device_id_8bytes]:<OK/ER:CALC_CRC>\r\n
Fields meaning linke in scan command.
Set new rom ID for RW1990.
Command letter is followed by 8 bytes in HEX format with new RW1990 ID:
nXXXXXXXXXXXXXXXX\r
Where XXXXXXXXXXXXXXXX is the new ID in HEX format
ATmega will replay with command, newd ID and CRC info:
nXXXXXXXXXXXXXXXX:<1/0:valid_crc>\r
Where:
- XXXXXXXXXXXXXXXX is the new ID in HEX format
- <1/0:valid_crc> - if "1" then CRC is valid, otherwise return "0" followed by HEX byte with valid CRC for given ID (for 7 first bytes)
Send to host new ROM ID.
No parameters after command, will return lines:
mXXXXXXXXXXXXXXXX:<1/0:valid_crc>\r\n
Where:
- XXXXXXXXXXXXXXXX is the new ID in HEX format
- <1/0:valid_crc> - if "1" then CRC is valid, otherwise return "0" followed by HEX byte with valid CRC for given ID (for 7 first bytes)
Start write of new ROM ID to RW1990.
No parameters after command, will return lines:
w<1/0>\r\n
Where:
- <1/0> - if "1" then ROM ID is OK (does not contains only "00"), 0 - new ROM ID is full of 0 and write won't be executed.
Write is performed in few steps:
- First is checkd if there is no "0" only in new ROM ID.
- If there are only zeros will be returned line:
1W:RW1990-WR:ZEROS\r\n
and write will not be performed
- If there are only zeros will be returned line:
- Next is printed line with ROM ID to be written:
1W:RW1990-WR:NEW:XXXXXXXXXXXXXXXX\r\n
- After this is called function
ow_rw1990_write_rom(uint8_t *new)
with parameter containing array of byte[8] with new ROM ID, In function:- There is enabled checking & correcting for Family code & CRC. If CRC and/or FamilyCode does not match then they are corrected before write - this is reported by 2 LSB bits in result.
- Now, is performed 1st 1-Wire reset, followed by SKIP ROM command,
- After SKIP ROM is short delay and then is performed 2nd 1-Wire reset,
- Now is issued command WRITE ROM 0xD5, and after command are being sent 8 bytes (64bits) of new ROM ID in special manner (see code for more info)
- After sending new ID there is a short delay,
- Now is performed 3rd 1-Wire reset,
- After bus reset is issued command READ ROM
- And the new ROM ID is being read from RW1990
- the read ROM ID is then compared with ROM ID that was written, if those match then no error bits are set.
The result of write function from 1-Wire lib is returned in next line (after 1W:RW1990-WR:NEW):
1W:RW1990-WR:RES=XX
Where XX is a byte in HEX format, which bits represent, not used bits are 0:
0b0xxxxxxx = OK
0bxxxxxxx1 = CRC was fixed
0bxxxxxx1x = Family code was fixed
0b1xxxxxxx = No presence pulse from 1st 1W-reset
0b1xxxx1xx = No presence pulse from 2nd 1W-reset after skip ROM
0b1xxx1xxx = No presence pulse from 3rd 1W-reset after writing new ROM
0b1xx1xxxx = Verify write FAILED (new read rom mismach)
So the result 0x00 , 0x01 , 0x02 , 0x03 - mean that RW1990 was programmed OK, but for 0x01..0x03:
- 0x01 - OK but CRC was corrected
- 0x02 - OK but Family code was corrected to 01 (DS1990A family code)
- 0x03 - OK but Family code & CRC was corrected.
If bit 7th is set (mask 0x80 ) then there occured errors, mask byte with bits above to see what error occured.
In forlder images
you can see my test board :D
The file rw1990-test_m32_16MHz_1w-PD7_USART38400_8N1.hex is a compiled flash for ATMega32 with hardware configured as above mentioned.
:sleeping: