Hardware documentation for Tessel modules

Scope

This document provides hardware overviews for each Tessel module:

• Accelerometer
• Ambient
• Climate
• GPS
• Infrared
• Relay
• RFID
• Servo

Accelerometer

Measures acceleration in the x, y, and z directions.

Quick overview:

Notes

• I2C address can be modified by shorting J3 – see MMA8452Q datasheet 5.11.1 Table 10.
• +x = towards the Tessel, +y = G3 --> GND, +z = up

Links to Hardware Information:

• Code: firmware, docs, examples
• Schematic(PDF)
• Schematic (DipTrace)
• Layout (DipTrace)
• Layout support file for silkscreen

Ambient

Measures ambient light and sound. Sound gain adjustable via R6.

Quick overview:

Notes

• Light signal path includes low pass filters with f_c = 1.6 Hz
• Sound signal path measures loudness via a half wave rectifier

Links to Hardware Information:

• Code: firmware, docs, examples
• Schematic(PDF)
• Schematic (DipTrace)
• Layout (DipTrace)
• Layout support file for silkscreen

Climate

Measure temperature and humidity

Quick overview:

Notes

Temperature of the climate module can be affected by proximity to the Tessel processor.

Links to Hardware Information:

• Code: firmware, docs, examples
• Schematic(PDF)
• Schematic (DipTrace)
• Layout (DipTrace)
• Layout support file for silkscreen

GPS

Global positioning system: position reference, movement speed & heading, time reference

Quick overview:

Notes

• The A2235-H is based on CSR SiRFstarIV chipset, which supports a novel GPS fix mode and a variety of low power states.
• The A2235-H supports two different data modes: NMEA and SiRF binary mode (also called OSP mode). Tessel GPS's default APIs use the module in NMEA mode.
• A-GPS is supported with client generated extended ephemeris up to 3 days.

Links to Hardware Information:

• Code: firmware, docs, examples
• Schematic(PDF)
• Schematic (DipTrace)
• Layout (DipTrace)
• Layout support file for silkscreen

Infrared

Communicate with and command household electronics using IR light

Quick overview:

Notes

• Receiving IR takes very little power. Transmission, on the other hand, uses a good deal of power.
• Receiver frequency is fixed at 38 kHz, although pin-compatible parts which operate at other frequencies presumably exist. Check your appliance's manual and/or the internet to make sure your hardware is compatible.

Links to Hardware Information:

• Code: firmware, docs, examples
• Schematic(PDF)
• Schematic (DipTrace)
• Layout (DipTrace)
• Layout support file for silkscreen

Relay

Switch large, high voltage loads

Quick overview:

Notes

• Relays are normally open (load disconnected) and will open should the module/Tessel lose power
• Current draw increases when the relays close (I_draw = 10mA + 40mA * [number of relays on])
• Rated to 240 V, 5 A (but please be careful)
• Insert and remove wires by pressing down on the connectors with a ballpoint pen (or similar).

Links to Hardware Information:

• Code: firmware, docs, examples
• Schematic(PDF)
• Schematic (DipTrace)
• Layout (DipTrace)
• Layout support file for silkscreen

RFID

Read and write from/to 13.56 MHz RFID cards and tags

Quick overview:

Notes

• Module can be switched to communicate over SPI with appropriate resistor pop option swaps
• Current is highest when transmitting and much lower most of the time
• A MiFare Classic card ships with the module
• Hardware-compatible with ISO-14443 RFID tags, including but not limited to: MiFare (Classic 1k, Classic 4k, Ultralight), DesFire, and FeliCa. Further information in the link.
• Compatible cards (consumer): Charlie, Clipper

Links to Hardware Information:

• Code: firmware, docs, examples
• Schematic(PDF)
• Schematic (DipTrace)
• Layout (DipTrace)
• Layout support file for silkscreen

Servo

Control up to 16 servos

Quick overview:

Notes

• An I2C LED PWM driver makes for a great servo driver too!
• 16 channels
• Tessel is a 3.3V device, so V_out on the PWM channels is 3.3 V (works for standard hobby servos)
• 5.5 mm barrel jack (center positive) for powering servos
• Can be used to control anything that needs PWM (speed controllers, gate drivers-to-FETs-big LEDs, etc.)

Links to Hardware Information:

• Code: firmware, docs, examples
• Schematic(PDF)
• Schematic (DipTrace)
• Layout (DipTrace)
• Layout support file for silkscreen