Table of Contents
hil_esc_output
Generates a PWM output value suitable for an ESC command.
Description
The hil_esc_output function generates an appropriate value to write to a PWM output to perform the given ESC command based on the given protocol and options. The PWM output value is written to the variable whose address is supplied in the pwm_output argument. This value is then written to the PWM output using a function such as hil_write_pwm.
For ESC protocols like standard PWM, OneShot and Multishot, the throttle value as a percentage (0% to 100%) is mapped to a pulse width in seconds. The PWM output mode should be configured as PWM_TIME_MODE (4) in the hil_set_pwm_mode function when using these protocols. The desired PWM period must also be configured using the hil_set_pwm_frequency functions.
The telemetry and command inputs are ignored unless the protocol is ESC_PROTOCOL_DSHOT.
For the DSHOT protocol, there are three inputs: throttle, telemetry and command. The throttle value is a percentage (0% to 100%) and the telemetry is a logical input indicating whether to include a telemetry request in the DSHOT output. The command input is used for special commands. A command value of 0 means "disarm", for instance. Command values from 0-47 are for special commands and the throttle value will be ignored in the output. A command value of 48 means "armed". In this case, the throttle value is included in the output value.
For DSHOT, the PWM output should be configured in PWM_RAW_MODE (6) in the hil_set_pwm_mode
function and DSHOT should be enabled in the card-specific options e.g. pwm0_dshot=1
via the
hil_set_card_specific_options function.
The PWM frequency will determine the bit rate for the DSHOT. For example, a PWM frequency of 600e3 will
result in DSHOT600 being output from the PWM output.
The table below enumerates the typical settings employed for various ESC protocols.
Protocol |
Description |
PWM Mode |
PWM Frequency |
ESC Constant |
---|---|---|---|---|
Standard PWM |
1 to 2 ms pulse every 20 ms. |
PWM_TIME_MODE (4) |
50 |
ESC_PROTOCOL_STANDARD_PWM (0) |
OneShot125 |
125 to 250 us pulse every 500us. |
PWM_TIME_MODE (4) |
2000 |
ESC_PROTOCOL_ONESHOT125 (1) |
OneShot42 |
42 to 84 us pulse every 168us. |
PWM_TIME_MODE (4) |
1/168e-6 |
ESC_PROTOCOL_ONESHOT42 (2) |
Multishot |
5 to 25 us pulse every 50us. |
PWM_TIME_MODE (4) |
20000 |
ESC_PROTOCOL_MULTISHOT (3) |
DShot150 |
16-bit packet at 150 kbaud. |
PWM_RAW_MODE (6) |
150e3 |
ESC_PROTOCOL_DSHOT (4) |
DShot300 |
16-bit packet at 300 kbaud. |
PWM_RAW_MODE (6) |
300e3 |
ESC_PROTOCOL_DSHOT (4) |
DShot600 |
16-bit packet at 600 kbaud. |
PWM_RAW_MODE (6) |
600e3 |
ESC_PROTOCOL_DSHOT (4) |
DShot1200 |
16-bit packet at 1200 kbaud. |
PWM_RAW_MODE (6) |
1200e3 |
ESC_PROTOCOL_DSHOT (4) |
DShot2400 |
16-bit packet at 2400 kbaud. |
PWM_RAW_MODE (6) |
2400e3 |
ESC_PROTOCOL_DSHOT (4) |
The DSHOT commands are unique to the ESC, other than disarm (0) and armed (48). The table below shows the commands implemented by KISS. Not every ESC is guaranteed to implement all of these commands, and other manufacturers may implement a different set of commands.
Command |
Value |
Description |
---|---|---|
DSHOT_COMMAND_DISARM |
0 |
Disarm. The motor will stop. |
DSHOT_COMMAND_BEEP_LOW |
1 |
Beep at low frequency. |
DSHOT_COMMAND_BEEP_MEDIUM_LOW |
2 |
Beep at medium-low frequency. |
DSHOT_COMMAND_BEEP_MEDIUM |
3 |
Beep at medium frequency. |
DSHOT_COMMAND_BEEP_MEDIUM_HIGH |
4 |
Beep at medium-high frequency. |
DSHOT_COMMAND_BEEP_HIGH |
5 |
Beep at high frequency. |
DSHOT_COMMAND_ESC_INFORMATION |
6 |
ESC information request (firmware version, serial number and settings sent over telemetry wire). |
DSHOT_COMMAND_ROTATE |
7 |
Rotate in one direction. |
DSHOT_COMMAND_ROTATE_OTHER |
8 |
Rotate in the other direction. |
DSHOT_COMMAND_3D_MODE_OFF |
9 |
3D mode off. |
DSHOT_COMMAND_3D_MODE_ON |
10 |
3D mode on. |
DSHOT_COMMAND_ESC_SETTINGS |
11 |
ESC settings request (settings will be saved over the telemetry wire). Not currently implemented. |
DSHOT_COMMAND_SAVE_SETTINGS |
12 |
Save settings. |
|
13-19 |
Reserved. |
DSHOT_COMMAND_ROTATE_NORMAL |
20 |
Rotate in the normal direction. |
DSHOT_COMMAND_ROTATE_REVERSE |
21 |
Rotate in the reverse direction. |
DSHOT_COMMAND_LED0_ON |
22 |
LED 0 on (BLHeli32 only). |
DSHOT_COMMAND_LED1_ON |
23 |
LED 1 on (BLHeli32 only). |
DSHOT_COMMAND_LED2_ON |
24 |
LED 2 on (BLHeli32 only). |
DSHOT_COMMAND_LED3_ON |
25 |
LED 3 on (BLHeli32 only). |
DSHOT_COMMAND_LED0_OFF |
26 |
LED 0 off (BLHeli32 offly). |
DSHOT_COMMAND_LED1_OFF |
27 |
LED 1 off (BLHeli32 offly). |
DSHOT_COMMAND_LED2_OFF |
28 |
LED 2 off (BLHeli32 offly). |
DSHOT_COMMAND_LED3_OFF |
29 |
LED 3 off (BLHeli32 offly). |
DSHOT_COMMAND_AUDIO_ON_OFF |
30 |
Audio stream mode on/off. |
DSHOT_COMMAND_SILENT_MODE |
31 |
Silent mode on/off. |
|
32-47 |
Reserved. |
DSHOT_COMMAND_ARMED |
48 |
Armed (normal operation). |
Prototype
t_error hil_esc_output(t_esc_protocol protocol, t_double throttle, t_boolean telemetry, t_dshot_command command, t_double* pwm_output);
Parameters
t_esc_protocol protocol
The ESC protocol for which the PWM output value will be generated.
t_double throttle
A fraction between 0.0 and 1.0 representing the throttle value from 0% to 100%.
t_boolean telemetry
When the ESC protocol is set to ESC_PROTOCOL_DSHOT, the telemetry parameter determines whether telemetry information is returned from the selected channel (true or false).
t_dshot_command command
When the ESC protocol is set to ESC_PROTOCOL_DSHOT, the commmand parameter represents the DSHOT command. Use DSHOT_COMMAND_ARMED when trying to control the motor throttle.
t_double * pwm_output
The address of a variable to receive the computed PWM output value.
Return value
The return value is 0 on success and a negative error code otehrewise. Error codes are
defined in quanser_errors.h
. A suitable error message may be retrieved using
msg_get_error_message.
Error codes
QERR_INVALID_ARGUMENT
One of the arguments is invalid.
Requirements
Include Files |
Libraries |
---|---|
hil.h |
hil.lib;quanser_runtime.lib;quanser_common.lib |
Examples
t_double value; t_error result = hil_esc_output(ESC_PROTOCOL_DSHOT, 0.1, false, DSHOT_COMMAND_ARMED, &value);
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