RoboSavvy Forum

Programming for AX-12

2009-03-01T15:55:11+01:00

Hi all. I have another question about the time delay of programming. As I know that Ax-12 have the feedback position, so how can I using this kind of method? let say I have movement1 and movement2. after the execution of movement1, wait for about 2 second, the movement2 are execute. So how we write this kind of programming using the feedback position of movement1, confirm the position of movement1(executed), then execute movement2 ? Thanks.

Statistics: Posted by Starlight — Sun Mar 01, 2009 3:55 pm

Programming for AX-12

2009-02-28T08:01:19+01:00

uint8_t packetchecksum;

void packet_start(uint8_t id, uint8_t length) {
checksum = id + length;
uart_send(0xff);
uart_send(0xff);
uart_send(id);
uart_send(length);
}

void packet_data(uint8_t *data, uint8_t length) {
uint8_t count = length;
uint8_t *ptr = data;
while (count--) {
uart_send(*ptr);
checksum += *ptr;
ptr++;
}
}

void packet_end(void) {
uart_send(~checksum);
}

void send_ping(uint8_t id) {
packet_start(id, PING_LENGTH);
packet_data(PING_DATA, PING_DATALENGTH);
packet_end();
}

is that the above code controlling 1 dynamixel ? I wanna control up to 14 dynamixel on the same time for sync write. from the user manual page 23, there is more like instruction(0x83), ID(0xfe), .etc.

Statistics: Posted by Starlight — Sat Feb 28, 2009 8:01 am

Programming for AX-12

2009-02-28T07:51:40+01:00

Hi. May I ask how to implementing a continuously rotating wheel ? from the manual, it state that set the CW and CCW angle limit to 0. then set the Goal Speed.

uart_send(0xff);
uart_send(0xff);
uart_send(0x0d);//ID
uart_send(0x07);//length
uart_send(0x03);//write_data
uart_send(0x06);//starting address: CW angle limit
uart_send(0x00);//CW angle limit
uart_send(0x00);
uart_send(0x00);//CCW angle limit
uart_send(0x00);
uart_send(0xe9);//checksum

~~waiting for transmit

uart_send(0xff);
uart_send(0xff);
uart_send(0x0d);//ID
uart_send(0x05);//length
uart_send(0x03);//write data
uart_send(0x20);//starting address: moving speed
uart_send(0x50);
uart_send(0x01);
uart_send(0x79);//checksum

while(TXSTAbits.TRMT==0);

LATCbits.LATC0 =1;

So the above code is the correct one?

Statistics: Posted by Starlight — Sat Feb 28, 2009 7:51 am

Re: Programming for AX-12

2009-02-27T22:14:19+01:00

Starlight wrote:
Or have anyone came out with better method for controlling up to 14 number of dynamixel without wasting lots of time in calculating the checksum and reduce the line of programming ?

The way we do it in libbioloid (check out the other threads on this) is to have a function to send the start of a packet, a function to send packet data and a function to send the end of a packet.

The logic goes something like this:

Code:: uint8_t packetchecksum; void packet_start(uint8_t id, uint8_t length) { checksum = id + length; uart_send(0xff); uart_send(0xff); uart_send(id); uart_send(length); } void packet_data(uint8_t *data, uint8_t length) { uint8_t count = length; uint8_t *ptr = data; while (count--) { uart_send(*ptr); checksum += *ptr; ptr++; } } void packet_end(void) { uart_send(~checksum); } void send_ping(uint8_t id) { packet_start(id, PING_LENGTH); packet_data(PING_DATA, PING_DATALENGTH); packet_end(); }

Please don't use the code above as-is without sanity checking it, it's written off the top of my head and probably has many bugs. It's more to illustrate a point

Statistics: Posted by StuartL — Fri Feb 27, 2009 10:14 pm

Programming for AX-12

2009-02-27T09:44:47+01:00

Hi all. currently I'm writing moving position for sync write. I'm using PIC18F4550, and for single dynamixel, it perform well. By the way, I wanna control up to 14 number of dynamixel, so it will waste a lots of time to calculate the checksum. So I came up with the following code:
(control only 2 number of dynamixel)

*******MOVING POSITION (SYNC WRITE)***********
uart_send(0xFF);
uart_send(0xFF);
uart_send(0xFE);
uart_send(0x0E);//LENGTH = (L+1)*N+4
uart_send(0x83);
uart_send(0x1E);//goal position
uart_send(0x04);//length of data to be written (1 dynamixel)
sendSW(1,0x0010,0x0150);
checksum_1 = sendSW (1,0x0010,0x0150);
sendSW(2,0x0220,0x0360);
checksum_2 = sendSW (2,0x0220,0x0360);
t_checksum = checksum_1 + checksum_2;
uart_send(0x4E+t_checksum);//total checksum

char sendSW (char id, int pos, int speed)
{
uart_send(id);//ID
uart_send((char)pos);
uart_send((char)(pos>>8));
uart_send((char)speed);//Moving Speed
uart_send((char)(speed>>8));
return(~(char)(id+(char)pos+(char)(pos>>8)+(char)speed+(char)(speed>>8)));//checksum
}

But it seem not exactly corret, is there any error or mistake in calculating the return value of checksum ?

Or have anyone came out with better method for controlling up to 14 number of dynamixel without wasting lots of time in calculating the checksum and reduce the line of programming ?

Thanks !

Statistics: Posted by Starlight — Fri Feb 27, 2009 9:44 am