protocol.md

Base Protocol SimplePacketComs

Protocol Definition

SimplePacketComs Theory of Operation

Our firmware uses an HID implementation built on the Adafruit TinyUSB stack.

Timing

When you send a command, what you are doing is queing up a packet to be sent. When you read a packet, you are reading the most recent packet recived. There is a thread internal to the command library that will manage the sending and reciving of packets. The round trip time for a packet from the library to the device and back is 2ms max. There is a delay between when you send a packet and when the latest response from that packet can be read. To send a request and wait 3ms, then read it back will always result in the latest data Alternantly using a state machine to manage sending and reciving to prevent busy waits is a much better option.

LED Light Ring

Set the color and brightness of the ring.

	ID	float	float	float
downstream Bytes	4	4	4	4
Contents downstream	2000	Hue 0.0 to 1.0	Saturation 0.0 to 1.0	Brightness (value) 0.0 to 1.0
upstream Bytes	4	---	---	---
Contents upstream	2000	---	---	---

ServoServer

Set the gripper value

NOTE this uses one byte as the value, not a float.

	ID	byte
downstream Bytes	4	1
Contents downstream	1962	Gripper value 0-180
upstream Bytes	4	---
Contents upstream	1962	---

Set Motor Setpoints With Time

Set the setpoint of the Motors with interpolation. Time is in milliseconds. The interpolation mode determines the trajectory the motor takes. Positions are in degrees.

	ID	float	float	float	float	float
downstream Bytes	4	4	4	4	4	4
Contents downstream	1848	mS duration of move	interpolation mode 0=linear,1=sinusoidal	motor 1 target position	motor 2 target position	motor 3 target position
upstream Bytes	4	---
Contents upstream	1848	---

Get Positions and Setpoint

	ID	float	float	float	float	float	float	float
downstream Bytes	4	---	---	---	---	---	---	---
Contents downstream	1910	---
upstream Bytes	4	4	4	4	4	4	4	4
Contents upstream	1910	the number of motors	motor 1 Setpoint	motor 1 position	motor 2 Setpoint	motor 2 position	motor 3 Setpoint	motor 3 position

Get Velocity data

	ID	float	float	float	float	float	float	float	float	float
downstream Bytes	4	---
Contents downstream	1822	---
upstream Bytes	4	4	4	4	4	4	4	4	4	4
Contents upstream	1822	motor 1 Velocity Mode Setpoint	motor 1 velocity	motor 1 computed effort	motor 2 Velocity Mode Setpoint	motor 2 velocity	motor 2 computed effort	motor 3 Velocity Mode Setpoint	motor 3 velocity	motor 3 computed effort

ERROR packet

If you send an ID that the device doesn't understand you will get this packet back. It happens when you send the wrong ID number, or forget to attach servers in the firmware to the coms stack.

	ID
downstream Bytes	4	---
Contents downstream	unknown by server	---
upstream Bytes	4	---
Contents upstream	99	---