Copy dallas keys. Record on rw1990 (rw1990.1)

Hello! Today I want to talk about how to make a device that allows you to copy Touch Memory company Dallas. The article is intended for those who have experience in programming in C / C ++ languages. I don’t intend to tell how the OneWire protocol works. On the Internet, a lot of information on this topic.



So, what we need for the manufacture of this device:



1) Atmega8

2) FTDI RL232 converts USB to USART

3) Driver for FTDI RL232

4) Programmer (I used USBasp)

5) Visual Studio

6) Atmel Studio

7) Breadboard



With this set you can move on. To get started, prepare a board on which to place the components.

I did it like this:

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Now let's define the parameters of USART atmega8. I have these:

1) Stop bit - 1

2) 9600boud

3) Parity bit - no



I will use the internal 4Mhz generator, so I will tune the UBRR register for this frequency. Here is the piece of code where the USART setup is going:

DDRD|=(1<<1); DDRD&=~(1<<0); UBRRH=0; UBRRL=25; UCSRB|=(1<<RXEN)|(1<<TXEN); UCSRC|=(1<<URSEL)|(1<<UCSZ0)|(1<<UCSZ1); 

It's time to disassemble the record protocol for rw1990 discs. The command to read the 8-byte code is identical with the dallas keys.



Writing to rw1990 happens like this:

1) Send a reset pulse, and expect the presence of a pulse;

2) Send the command 0xD1, thereby allowing the recording;

3) Time slot, send a logical "0" (see Figure 1);

4) Send a reset pulse and wait for the presence of a pulse;

5) Send the write command, 0xD5;

6) We send an 8-byte code (all bits are inverted), the transfer is different from the oneWire protocol (see Figure 1);

7) Send a reset pulse and wait for the presence of a pulse;

8) Send the command 0xD1, thereby prohibiting the recording;

9) Time slot, send a logical "1" (see Figure 1).



Figure 1:







A piece of code where the recording occurs:

 bool onewire_init(){ onewire_low(); _delay_us(480); onewire_high(); _delay_us(2); for(uint8_t i= 60;i;i++){ if(!onewire_level()){ while(!onewire_level()); return true; } _delay_us(1); } return false; } void time_slot(uint8_t data){ onewire_low(); if(data) _delay_us(6); else _delay_us(60); onewire_high(); _delay_ms(10); } void rw1990_write_bit(uint8_t data){ onewire_low(); if (data) _delay_us(6); else _delay_us(60); onewire_high(); _delay_ms(2); } void rw1990_write(uint8_t data){ for(uint8_t i=0;i<8;i++){ rw1990_write_bit(data & 0x01); data>>=1; } } bool rw1990_newcode(uint8_t* buf){ if (onewire_init()){ onewire_send(0xD1); time_slot(0); }else return false; if(onewire_init()){ onewire_send(0xD5); for(uint8_t i=0;i<8;i++){ rw1990_write(~buf[i]); } }else return false; if (onewire_init()){ onewire_send(0xD1); time_slot(1); }else return false; return true; } 

I hope it is clear. We still need to write an application that will communicate with the microcontroller. That is, we will send requests to read and write the key to the microcontroller from the computer. I will lay out all source codes under a topic. The application is quite simple.



However, the video shows everything.





Of course, it was possible to do everything in OOP style, but for some reason I decided so.







The code, of course, is not the best, because I tried to write faster, but it still works great.



This is what I got at the end:



















And here is the video: