206 Swarm Microrobot Drug Delivery FSM :: Quicker, easier and cheaper to make your own chip!

How it works

This project implements a finite state machine (FSM) for a simplified swarm microrobot drug delivery system. The design detects blood clots, communicates clot information to nearby robots, and controls drug release and motor movement behavior.

The system uses two external inputs:

clot_detected (ui_in[0]) — local blood clot detection sensor clot_nearby (ui_in[1]) — RX communication signal indicating another nearby robot detected a clot

The FSM has four states:

RANDOM_WALK Default idle state where the robot moves normally. RELEASE_DRUG Triggered when a clot is locally detected and the robot still contains drug. The robot: releases the drug transmits a clot detected TX signal permanently clears its internal drug memory CLOT_NO_DRUG Triggered when a clot is detected after the drug has already been used. The robot: transmits clot detected TX transmits no-drug TX does not release drug WALK_AWAY Triggered after clot detection or when a nearby clot RX signal is received. All four motor outputs are enabled to move the robot away from the clot region.

The design internally stores whether the robot still contains drug using a register initialized during reset.

How to test

Apply reset (rst_n = 0, then rst_n = 1). The FSM initializes to RANDOM_WALK with the drug loaded. All uo_out bits are 0.
Hold idle (ui_in = 0) for one clock cycle. The FSM remains in RANDOM_WALK. All uo_out bits stay 0. This confirms no spurious transitions occur.
Set ui_in[0] = 1 to simulate a local clot detection while the drug is still available. The FSM transitions to RELEASE_DRUG. uo_out[0] goes HIGH (drug release command). uo_out[1] goes HIGH (clot detected TX). uo_out[2] remains LOW because the drug is still present during this cycle. Motors remain off.
Next clock cycle (clear ui_in). The FSM transitions to WALK_AWAY and contains_drug clears to 0. uo_out[0] and uo_out[1] go LOW. uo_out[2] goes HIGH (no drug TX). uo_out[3] through uo_out[6] go HIGH (all four motors on).
Next clock cycle. The FSM returns to RANDOM_WALK. Motors turn off. uo_out[2] remains HIGH because the drug is permanently gone.
Set ui_in[0] = 1 again to detect a clot without any drug. The FSM enters CLOT_NO_DRUG. uo_out[0] stays LOW (no drug to release). uo_out[1] goes HIGH (clot detected TX). uo_out[2] remains HIGH (no drug).
Next clock cycle (clear ui_in). The FSM transitions to WALK_AWAY. uo_out[3] through uo_out[6] go HIGH. uo_out[2] stays HIGH.
Next clock cycle. The FSM returns to RANDOM_WALK again.
Apply reset again (rst_n = 0, then 1) to reload the drug. Now set ui_in[1] = 1 to test the clot_nearby path. The FSM enters WALK_AWAY directly. uo_out[3] through uo_out[6] go HIGH. uo_out[2] stays LOW because the drug is still loaded. No release command, no clot TX.
Next clock cycle (clear ui_in). The FSM returns to RANDOM_WALK. All outputs return to 0.

Test Procedure

Step	Action	ui_in[1:0]	State	uo_out[6:0]	Description
1	Reset	00	RANDOM_WALK	0000000	Robot initializes with drug loaded
2	Idle	00	RANDOM_WALK	0000000	No inputs, robot stays wandering
3	Clot + drug	01	RELEASE_DRUG	0000011	Drug release command and clot TX go HIGH
4	Auto	00	WALK_AWAY	1111100	Motors on, drug permanently cleared
5	Auto	00	RANDOM_WALK	0000100	Back to wander, no-drug flag stays HIGH
6	Clot, no drug	01	CLOT_NO_DRUG	0000110	Clot TX HIGH, no release command
7	Auto	00	WALK_AWAY	1111100	Motors on
8	Auto	00	RANDOM_WALK	0000100	Return to wander
9	Reset + nearby	10	WALK_AWAY	1111000	Drug reloaded, dodge on neighbor signal
10	Auto	00	RANDOM_WALK	0000000	All outputs LOW, drug still loaded

Note: uo_out[7] is hardwired LOW and omitted from the table.

External hardware

No external hardware used in project

#	Input	Output
0	clot_detected_sensor	release_drug_cmd
1	clot_nearby_rx	clot_detected_tx
2		no_drug_tx
3		motor1_on
4		motor2_on
5		motor3_on
6		motor4_on
7

206 Swarm Microrobot Drug Delivery FSM