Change servo signal

Change signal parameters

Most servomotors obey to the standard PWM signal of period 20 ms and pulse length between 1 and 2 ms. Should you need a different signal, it can be modified in the servo_standard.luc file (line 18):

const MIN_T = 1; // min pulse (ms)  
const MAX_T = 2; // max pulse (ms)  
const PERIOD = 20; // period (ms)  

Note that this will affect the signal for all servos. In order to have servos with the standard and with the modified parameters, you will need to duplicate the servo_standard.luc file in the Au/Au+/Cu project (e.g. create a servo_standard_unconv.luc), create instance of the duplicated module in the *_top.luc file and allocate the inputs and outputs. Example for two servos with the modified parameters:

au__top.luc (line 132):

// declaration
servo_standard servo_controller[NUM_SERVOS-2];
servo_standard_unconv servo_controller_2[2]; // servo signals with new parameters

au_top.luc (line 323):

// input/output assignments
servo_controller.position = position.q[NUM_SERVOS-1:2];
servo_controller_2.position = position.q[1:0];
servo_sig.update = servo_sig_update.q;
servo_sig.signal_in[NUM_SERVOS-1:2] = servo_controller.servo;
servo_sig.signal_in[1:0] = servo_controller_2.servo;

Change switch-off delay

In servo_stop.luc (line 20):

dff count_sig[30]; // count until ~ 10 sec @ 100MHz

Since the clock frequency is 100 MHz, then the switch-off delay of the servos is:

You can change the bit depth of count_sig to adjust the switch-off delay, for instance:

line 16	delay (s)
dff count_sig[28];	2.68
dff count_sig[29];	5.37
dff count_sig[31];	21.47
dff count_sig[32];	42.99