Control legs separately

[kissgyula]

Is it possible to control the legs separately with this modification? I don't specifically want to use it as a table leg, and I would need it to be able to adjust the two legs completely independently. In addition, I would also like to know if it is possible to use it with only one leg connected?

[gcormier]

Out of the box I doubt it will work. But with some code modifications, it should absolutely work with 1 leg only.

[kissgyula]

Thank you for the answer!

I try to study the code, and find there is node_a and node_b, and also enc_a and enc_b where the lin.recv reads the motor states as I understand.

But the lin.send part is what I not understand fully. Is the cmd[0] = enc_target & 0xFF; and cmd[1] = enc_target >> 8; around line 1062 in the code, will set the target for the two motors? If I set this to two different encoder targets, the legs will move to a different position?

[AnAnalogGuy]

Controlling one leg alone potentially is possible by just connecting one leg of the table to the control unit.
But i don't see how two connected legs could be controlled independently by one control unit, as far as I understand the electrical circuit of the table, the legs are not controlled independently.

[gcormier]

megadesk/code/src/megadesk.cpp

Lines 992 to 997 in e1840cc

	// lastly send lin command to PID 18
	cmd[0] = enc_target & 0xFF;
	cmd[1] = enc_target >> 8;
	cmd[2] = lin_cmd;
	delayUntil(5);
	lin.send(18, cmd, sizeof(cmd));

This is where megadesk sends the command (PID 18).

Having 1 motor would not change anything as the motors are listening for this command.

The only time the individual legs come into play is when they respond to the height query for their unique PID.

megadesk/code/src/megadesk.cpp

Lines 818 to 843 in e1840cc

	// Recv from PID 09
	uint8_t chars = lin.recv(9, node_b, sizeof(node_b));
	uint16_t enc_b = node_b[0] | (node_b[1] << 8);
	if (chars != sizeof(node_b)+1) {
	#ifdef SERIALERRORS
	#ifdef SERIALCOMMS
	writeSerial(response_error, enc_b, chars, badPID9Marker);
	#endif
	/*
	#ifdef FEEDBACK
	if (feedback) playTone(NOTE_A4, PIP_DURATION);
	#endif
	*/
	#endif
	return 0;
	}
	delayUntil(5);
	// Recv from PID 08
	chars = lin.recv(8, node_a, sizeof(node_a));
	uint16_t enc_a = node_a[0] | (node_a[1] << 8);
	if (chars != sizeof(node_a)+1) {
	#ifdef SERIALERRORS
	#ifdef SERIALCOMMS
	writeSerial(response_error, enc_a, chars, badPID8Marker);
	#endif

This is where we check the height of both motors, and subsequently use min/max values between the two to decide which is going to determine our actual height. You would want to only query, say, PID 8 and use that for the current height status.