1. A more in depth look (XUF216-512-TQ128)
XMOS Powered Car
A more in depth look
(XUF TQ128)

2. XMOS MCU Overview 16 Cores across 2 Tiles 512K single cycle SRAM
Each tile shares 256K of 512K
Single cycle instructions(except divide)
Entirely deterministic, no cache, no flash pages
2MB on-chip flash memory
Core speeds from 62.5 MHz up to 100 MHz
(100 MHz up to 5 threads, 500/N_cores MHz beyond 5)

3. In actuality… Dual core 500 MHz RISC MCU Hardware task scheduler
Provides 0 overhead context switching
8 sets of internal registers
Event driven as opposed to interrupt driven
Uses Xc a very C-like language
No FPU, but is 32-bit

4. Pros Many threads running at the same time
Can daisy chain multiple MCU’s for expansion
Xc provides C++-like type checking
Buffered, timed, and flexible I/O ports
10ns event response time
Able to debug over USB via XTAG (Custom JTAG)
Flexible thread placement, or automatic placement
All software, pick your own peripherals

5. Cons All software, pick your own peripherals
Exceptions built-in to keep all your hacks in check
Tools are not without issues, including compiler
Pointer and array semantics are very strict
Xc requires some ugliness as a template
SRAM is shared for Stack, Code, and Data
I/O only 1.0V - 3.3V compatible
Physical board layout not straight forward, timing requirements for I/O and core voltages, PLL noise

6. Thread() {
While (1) {
Select {
Case my_func() -> int ret_val: {
//Some Code }

8. Main() {
Iface1 myIface1;
Iface2 myIface2[2];
Par {
thread1(myIface1, myIface2);
thread2(myIface1, myIface2[0]);
thread3(myIface2[1]); }

9. USB
XTAG
The board
Reset
24MHz MEMS
LED
1.0V / 3.3V

10. New reset circuit

11. Hardware Setup
Hardware setup
Serial
1.2Mbps I2C
I2C
I2C
PWM
PWM

12. Teensy 3.6 Software Manages bluetooth messaging
Manages all data logging
Data logged is different between manual and auto
Receives structure of data from XMOS during runtime
Controls headlights via bluetooth or button

13. XMOS Software Reads wheel sensors which provide speed and distance
Reads data from IMU which provides orientation
In manual mode reads PWM values from receiver and sends them to ESC/Steering servo
In automatic mode manages ESC/Steering through PID control.
Provides car state to Teensy for logging over I2C
Manages recording/driving/auto states

14. PC Software Allows Path viewing and editing
Compare driven path to intended path
OpenGL based, written in C++
All pathing files must be local, no remote car access
Allows taking screenshots for sharing
Auto-scale path window for maximum resolution
Properly scales for high DPI screens