MOWE Hardware - OUWECAD/MOWE GitHub Wiki

##Table of Contents Definitions
Available Modules
Optical Specifications
Electrical Specifications
Mechanical Specifications
UART Connections
Useful Datasheets

Definitions

  • Module: A small PCB with a specific geometric shape (hexagon, pentagon, triangle, or rectangle). Each module is a single optical point.
  • Optical point: An optical transmitter, receiver, or transceiver centered on the top surface of a single module. It might consist of multiple LEDs, VCSELs, or PDs but it will still be considered as a single optical point for optical aperture calculations.
  • Array: Multiple modules soldered together form a single array. Arrays can be made flat, spherical or curved and they form continuous or discontinuous surfaces. A single array might even consist of separate "islands" connected together by wires short enough to facilitate error-free serial UART communications (< 1m).
  • Frame: Some arrays might need structural support and protection. This is done via plastic frames or hollow structures usually made using 3D printing.
  • Terminal: The array with its frame, attachments, cables and with/out a central controller constitute a complete optical communication terminal.
  • Optical resolution: The distance between two adjacent optical points (modules) center-to-center. Arrays usually have homogeneous optical resolution across all modules.
  • Edge pcb connectors: Small areas of exposed copper positioned at module edges and sides for physically and electrically connecting adjacent modules. Larger edge connectors are used for power connection (Top: +3.3V, Bottom: GND), while smaller ones are used for signal connection and networking (Top: TXD, Bottom: RXD).
  • Array ports: Called serial ports as well. These are the serial communication ports that connect each module to its neighbors. Named P1 to P6 in hexagons (numbered 13 to 18) and P1 to P5 in pentagons (numbered 11 to 15). The default configuration for these ports is to have TXD on the top side and RXD on the bottom side. In order to connect two adjacent modules, the TXD and RXD lines must be swapped internally in one of them. This can be done easily in ST MCUs by updating the UART swap bit.

Available Modules

MOWE hardware consists currently of the following modules:

  • HO01R1: Hexagon receiver with VEMT3700/VEMT3700F - 30mm optical resolution.
  • HO01R2: Hexagon receiver with VEMT3700/VEMT3700F - 20mm optical resolution.
  • HO01R3: Updated version of H01R1. Port numbers are replaced with port names and UART/port distribution was modified.
  • HO02R0: Hexagon transmitter with VSMY2850G - 30mm optical resolution.
  • HO02R1: Hexagon transmitter with VSMY2850G - 20mm optical resolution.
  • HO02R2: Updated version of H02R0. Transistor footprint is fixed. Port numbers are replaced with port names and UART/port distribution was modified.
  • PO01R0: Pentagon receiver with VEMT3700/VEMT3700F compatible with hexagons 30mm optical resolution.
  • PO02R0: Pentagon transmitter with VSMY2850G compatible with hexagons 30mm optical resolution.

3D modules

Top-Bottom 3D representation of MOWE modules. (Open image in a new tab for 1:1 scale.)

Optical Specifications

Module HO01R1/HO01R3 HO01R2 HO02R0/HO02R2 HO02R1 PO01R0 PO02R0
LED wavelength N/A N/A 850nm 850nm N/A 850nm
LED angle of half sensitivity N/A N/A ±10° ±10° N/A ±10°
PD wavelength 850nm, 940nm 850nm, 940nm N/A N/A 850nm, 940nm N/A
PD angle of half sensitivity ±60° ±60° N/A N/A ±60° N/A

Detailed MOWE optical characterization experiments have been conducted at The University of Tulsa. Experiment results and graphs can be accessed here.

Electrical Specifications

This table provides some useful electrical characteristics for current MOWE modules. The streaming speed is achieved by direct memory access (DMA) and depends on the configured MCU clock frequency and USART baudrate. Probably, higher streaming speeds up to 2 or 4 Mbps can be achieved. The power consumption measurement is for the module active state and varies depending on whether the transmitter LEDs are on or off. Configuring the module to sleep or enter low power modes greatly reduces average and total power consumption.

Parameter Value
Array architecture Peer to peer
Streaming speed Up to 1 Mbps
MCU STM32F091RCT6 for 30mm modules
STM32F091CBU6 for 20mm modules
Module power consumption (mW) 40-66

Mechanical Specifications

Module weight and cost are not to be taken precisely rather as rough estimates to aid in planning projects. Note that cost is calculated per module for a minimum order of 1000 pieces and varies considerably depending on your supplier.

Module HO01R1/HO01R3 HO01R2 HO02R0/HO02R2 HO02R1 PO01R0 PO02R0
Optical resolution 30mm 20mm 30mm 20mm 30mm 30mm
Module shape hexagon hexagon hexagon hexagon pentagon pentagon
Module thickness 3.2mm 3.2mm 3.2mm 3.2mm 3.2mm 3.2mm
Module weight 2g 1g 2g 1g 2g 2g
Module cost $4-$6 $4-$6 $4-$6 $4-$6 $4-$6 $4-$6

Module mechanical dimensions can be obtained here.

UART Connections

HO01R1, HO02R0

Name(TX Pin, RX Pin) UART Port Label
P1 (PA_2, PA_3) USART 2 13
P2 (PC_4, PC_5) USART 3 14
P3 (PC_6, PC_7) USART 7 15
P4 (PC_8, PC_9) USART 8 16
P5 (PC_10, PC_11) USART 4 17
P6 (PC_12, PD_2) USART 5 18

HO01R2, HO02R1

Name(TX Pin, RX Pin) UART Port Label
P1 (PA_2, PA_3) USART 2 13
P2 (PA_4, PA_5) USART 6 14
P3 (PB_10, PB_11) USART 3 15
P4 (PB_3, PB_4) USART 5 16
P5 (PB_6, PB_7) USART 1 17
P6 (PA_0, PA_1) USART 4 18

HO01R3, HO02R2

Name(TX Pin, RX Pin) UART Port Label
P1 (PA_2, PA_3) USART 2 P1
P2 (PC_4, PC_5) USART 3 P2
P3 (PC_6, PC_7) USART 7 P3
P4 (PC_8, PC_9) USART 8 P4
P5 (PC_10, PC_11) USART 4 P5
P6 (PB_6, PB_7) USART 1 P6

PO01R0, PO02R0

Name(TX Pin, RX Pin) UART Port Label
P1 (PC_12, PD_2) USART 5 11
P2 (PA_2, PA_3) USART 2 12
P3 (PC_4, PC_5) USART 3 13
P4 (PC_8, PC_9) USART 8 14
P5 (PC_10, PC_11) USART 4 15

Useful Datasheets

MCU

Optics