Baud rate problem

[Starlight]

Hi. Currently I'm successful get the response from the AX-12 using PIC18F4450 using default baud rate of 1Mbps. By the way, I'm accidentally changing the baud rate to 645161.29bps. the code as below:
uart_send(0xFF);
uart_send(0xFF);
uart_send(0x01); //ID

uart_send(0x09); //LENGTH
uart_send(0x03); //INSTRUCTION = WRITE_DATA
uart_send(0x03); //START ADDR (ID)
uart_send(0x02); //NEW ID
uart_send(0x1e);
uart_send(0x01);
uart_send(0x01);
uart_send(0x01);
uart_send(0x01);
uart_send(0xcb);

Now my PIC can't set the baud rate as close to the baud rate of AX-12(0x1e). So is there any solution to reset the baud rate of AX-12 to the factory's default baud rate (1Mbps) ?Thanks.

[RandomMatt]

You need to use the bootloader to reset the eeprom. (This will make your servo have ID=1).

1) enter the bootloader. You need to send many '#' characters to the servo (at 57600 baud) as it turns on (within ~60ms). The bootloader should respond with a '*'. The led should remain on.

2) reset the eeprom. send a 'c', wait for a '*'.

3) enter application mode. send an 'a', wait for a '*'. Followed by a 'g'.

--

You may also want to 'lock' the servo to stop this kind of mistake... just write a 0x01 to location 47. You'll still be able to control the torque, led, speed, position but you will not be able to mess up the id, baud rate, automatic turnoff etc.

[i-Bot]

By the way, I'm accidentally changing the baud rate to 645161.29bps.

I think it is 64516.128bps not 645161.29bps if you entered 0x1E.

If you get within 10% on the PIC you should be OK, that should be possible to communicate without error.

Why are you setting the other locations beyond the ID and baud rate ?

[Starlight]

Why are you setting the other locations beyond the ID and baud rate ?

Actually this is my first time using the AX-12 actuator. In the beginning, I just want to change the default ID of 1 to ID 2 but I forgot after we send the start address code (0x03), the following address will be follow the item in control table in sequence including baud rate, return delay time, etc.

You may also want to 'lock' the servo to stop this kind of mistake... just write a 0x01 to location 47. You'll still be able to control the torque, led, speed, position but you will not be able to mess up the id, baud rate, automatic turnoff etc.

I should know this kind of solution early. Thanks RandomMatt.

[Starlight]

i tried method below, but it ax-12's LED keep light on after i restart the ax-12.
and it seems i could not have any response at 1 M after i tried the method..

1) enter the bootloader. You need to send many '#' characters to the servo (at 57600 baud) as it turns on (within ~60ms). The bootloader should respond with a '*'. The led should remain on.

2) reset the eeprom. send a 'c', wait for a '*'.

3) enter application mode. send an 'a', wait for a '*'. Followed by a 'g'.

Is the LED of AX-12 should keep ON after i restart the AX 12?

[RandomMatt]

The led should remain on when step 1 is successful. It should go off again after you send the 'g' in step 3.

--

If you can, just attach a console of some sort(**) to the servo (at 57600) and you'll be able to see what is happening. (you may want to send an 'h' to get the help - and you really don't want to send an 'l').

(**) I did this by using the CM5 to effectively bridge the two UARTs (one is at TTL level, the other RS232). How many UARTs does your PIC have?