OpenEmbedded for the Chumby

Resources for running OpenEmbedded on the Chumby Hacker Board

Chumby Hacker Board Illustrated

Note that connection labels correspond to the identifiers on the Version 1.0 schematics.

Front of Board

Chumby Hackers Board Front

JP300

5VDC Power : Requires a regulated 5VDC power supply, positive tip, 3.5mm OD, 1.4mm ID barrel jack (aka a 3.8mm or 4mm connector).

Schematics indicate 2A peak. According to AdaFruit the power draw for the subsystems is roughly:

  • 300 mA for the base hardware (processor, RAM, SD card),
  • 200 mA for the USB hub (not including power to the USB devices),
  • 300 mA for a speaker plugged into the 2W output,
  • 500 mA max for charging a Lipoly battery.

P100

Li-poly battery connector : JST B3B-EH-A connector.

If powering from a Li-poly, USB0 will be powered, 1 and 2 will not.
There is a fourth USB connection on the GPIO header which is also powered by the Li-poly boost system. ref

P102

Serial JTAG header - 0.1” male header (DNP)

  • Pin 1 : 3.3v
  • Pin 2 : DEBUG
  • Pin 3 : PSWITCH
  • Pin 4 : GND

P104

Rotary Quadrature Encoder (no connector, solder points only)

  • Pin 1 : ROTARYA
  • Pin 2 : GND
  • Pin 3 : ROTARYB

P200

9x2 header : USB, I2C and GPMI

The following signals are available (by pin number)

Bottom Row, Left to Right

  • 1 - 5V
  • 3 - USBC1 N
  • 5 - USBC1 P
  • 7 - GND
  • 9 - Vid to Ext
  • 10 - i2C SCL
  • 11 - i2C SDA
  • 15 - 3.3V
  • 17 - LCD XP
  • 19 - LCD YP
  • 21 - LCD XM
  • 23 - LCD YM
  • 25 - HOST TO CP UART

Top Row, Left to Right

  • 2 - GPMI D00
  • 4 - GPMI D01
  • 6 - GPMI D02
  • 8 - GPMI D03
  • 10 - GPMI D04
  • 12 - GPMI D05
  • 14 - GPMI D07
  • 16 - GPMI D06
  • 18 - OSC TO FM
  • 20 - PWM2
  • 22 - CHUMBY BEND
  • 26 - CP TO HOST UART

P400

LRADC1 : Low Resolution Analog to Digital Converter

  • Pin 1 : LRADC1 (CPU)
  • Pin 2 : connected to pin 39 of P401 (why?)

P401

22x2 Header, LCD Connector

Top Row, Right to Left

  • 1 : GND
  • 3 : LCD T B1
  • 5 : LCD T B3
  • 7 : LCD T B5
  • 9 : LCD T G0
  • 11 : LCD T G2
  • 13 : LCD T G4
  • 15 : GND
  • 17 : LCD T R1
  • 19 : LCD T R3
  • 21 : LCD T R5
  • 23 : LCD VSYNC T
  • 25 : LCD DOTCLK
  • 27 : LCD ENABLE T
  • 29 : LED A
  • 31 : LCD WR E
  • 33 : LCD CS
  • 35 : LINE1 INL
  • 37 : GND
  • 39 : LRADC1 EXT
  • 41 : LCD XP
  • 43 : LCD XM

Bottom Row, Right to Left

  • 2 : LCD T B0
  • 4 : LCD T B2
  • 6 : LCD T B4
  • 8 : GND
  • 10 : LCD T G1
  • 12 : LCD T G3
  • 14 : LCD T G5
  • 16 : LCD T R0
  • 18 : LCD T R2
  • 20 : LCD T R4
  • 22 : P 3.3V
  • 24 : LCD HSYNC T
  • 26 : GND
  • 28 : LCD RESET
  • 30 : LED K
  • 32 : LCD RS
  • 34 : LCD DET
  • 36 : LINE1 INR
  • 38 : VDDA
  • 40 : LRADC0
  • 42 : LCD YP
  • 44 : LCD YM

P406

PWM2 : Pulse Width Modulation

  • Pin 1 : GND
  • Pin 2 : PWM2 (CPU)

P500

USB2 : USB Type A Female

P503

USB1 : USB Type A Female (is this really USB4?)

Note that the power to this port (and P500?) is software controlled and may be off at power-up. It can be enabled as explained here.

SW400

DPad switch type EVQQ7. The Data sheet is available. Sample code is available.

  • A : GPMI CE0n : BANK2_PIN28
  • B : GPMI WPn : BANK0_PIN23
  • C : GPMI WRn : BANK0_PIN24
  • D : GPMI RDn : BANK0_PIN25
  • E : PWM4 : BANK_1_PIN30 (aka CHUMBY BEND)

Accelerometer

A Freescale MMA7455L 3-axis accelerometer with adjustable sensitivity from +-2G to +-8G is accessible over I2C at device address 0x1D.

The Datasheet is available, sample code is available.

Schematic

Green LEDs

The 4 green LEDs are connected to the following GPIO pins:

  • GPMI_D00
  • GPMI_D01
  • GPMI_D02
  • GPMI_D03

Importantly, before any of the LEDs can be used, the transistor on GPMI_RDY0 must be turned on to ground the LEDs.

Sample code is available.

Schematic

Comments