TinyGrid85

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Tindie-larges-v2.png

TinyGrid85 - ATTiny85 Breadboard

We love Arduinos and breadboarding but we often end up with projects which are really too small to waste an entire Arduino. We also wanted some way to breadboard our designs with an ATTiny85 part. Often times we just want one or two boards and find it hard to justify a new board spin.

A big frustration that we have with the Arduino is the lack of proper mounting holes. We think that boards should have mounting holes even if it costs a little extra for the PCB. And the mounting holes should take common hardware like #4-40 or M3 screws. Stuff we can buy at our local hardware store.

So we designed the TinyGrid85.

TinyGrid85-X2-cca-001.JPG

Features

  • ATMEL ATTiny85 Microprocessor (or compatible 8-pin part)
  • Arduino Compatible (works with Arduino bootloader and Arduino IDE)
  • Prototyping area with power/ground connections
    • Brings out all 5 I/O lines and the reset line to grid columns
    • Laid out like a breadboard with vertically connected traces.
    • Power and Ground horizontal connections though all columns
    • Labeled (with letter numbers) for easy documentation
  • H1 - Jumper to select regulator or remove for ISP +5V
  • H2 - ISP Download Header (ATTiny85-Programming)
  • AP1117 5V Power Regulator with generous area under the regulator for heat dissipation
  • 2.1mm Connector for AC adapter 7-9V input
  • (4) 4-40 or M3 screw holes for solid mounting
  • 49x49 mm board

Connectors

H1 - VREG Jumper

  • Install to power board from the on-board regulator
  • Remove when connecting powered ISP cable

H2 - ISP Connector

Tiny85-ISP-Conn.PNG

How to program using an Arduino UNO running ArduinoISP.

ATtiny45-85.png

Grid Layout

The grid is laid out as 12 columns and 10 rows. Power and Ground lines are bused horizontally on the center rows. The columns are split as shown above and below the Power/Ground rows.

TinyGrid85-grid.PNG

PWB Silkscreen

TinyGrid85-X2.png

Schematic Diagram

PDF schematic

Parts List/Assembly Order

TinyGrid85 Assembly Sheet

Description Qty Reference Designator Part Type
AP1117-5.0 1 U2 SOT223
8 pin socket 1 U1 DIP-8__300 ֠optional socket
0.1uF 5 C1-C5 Cap, 0.1" spacing
10K 1 R1 Resistor, 1/4W
10uF 1 C6 Cap, 0.15" spacing
CONN_2 1 H1 PIN_ARRAY_2X1
Shunt_2 1 H1 Shunt
CONN_3X2 1 H2 pin_array_3x2
DCJ0202 1 J1 JACK_2.1MM
ATTINY85 1 U1 In socket
GVS Option 1 Grid 2x6
GVS Option 1 Grid 1x6

Board Dimensions

TinyGrid85-Dimensions.PNG

Factory Test Procedure

These are the tests that we run on TinyGrid85 before it leaves the Production facility.

Bare board tests

  • The bare boards are electrically tested by the PWB manufacturer.
    • This ensures that the boards are identical.
    • We have had no PWB issues to date and have had dozens of batches of boards built by this manufacturer.

Basic board tests

  • The bare boards are electrically tested by the PWB manufacturer.
  • The following steps are done with the parts all installed on the PCB.
  • Remove H1 (VREG) jumper
  • Program the Microprocessor
  • Disconnect card from ISP connector
  • Power Tests
    • Power card at 9V on barrel connector
    • Check output of the regulator from power to ground
      • Power is on the header, H1, on the pin nearest the regulator
      • Ground is on pin 4 of the Microprocessor
      • Measure 5V +/- 0.1V
  • Install H1 (VREG) jumper
  • Verify LEDs cycle by connecting one LED at a time (uses LED-Test board)
    • Disconnect 9V
    • Remove H1 (VREG) jumper
  • Reconnect ISP cable
  • Download BareMinimum sketch (leaves board with all pins set to input - safest option).

GVS board tests

  • The bare boards are electrically tested by the PWB manufacturer.
  • The following steps are done with the parts all installed on the PCB.
  • Remove H1 (VREG) jumper
  • Power Tests
    • Power card at 9V on barrel connector
    • Check output of the regulator from power to ground
      • Power is on the header, H1, on the pin nearest the regulator
      • Ground is on pin 4 of the Microprocessor
      • Measure 5V +/- 0.1V
      • Remove 9V
  • Program the Microprocessor
  • The GVS board has connectors for all pins
    • Verify LEDs cycle by connecting LED-Test board
  • Disconnect card from ISP connector
  • Install H1 (VREG) jumper
  • Connect 9V power
  • Verify LEDs cycle
    • Disconnect 9V
  • Remove H1 (VREG) jumper
  • Reconnect ISP cable
  • Download BareMinimum sketch (leaves board with all pins set to input - safest option).

Example - Opto-Isolated Logic Probe

This is the prototype circuit for the TinyOptoProbe board.

TinyGrid85-OptoPulse.JPG