This is the revision B version of the Orient5 module.

Orient5 Module (Revision B)

Table of Contents

• 1. Introduction
• 2. Programming
• 3. Hardware
  • 3.1 Circuit Schematic
  • 3.2 Printed Circuit Board
  • 3.3 Module Insertion
• 4. Software
• 5. Issues

1. Introduction

The Orient5 module manages 5 channels of orientation information -- 3 axes of acceleration and 2 axes of magnetic bearing. The accelerometer is cabable of measuring platform tilt (for a non-accelerating platform) by detecting the Earth gravitational acceleration. The magnetic bearing module can detect 360 degrees of magnetic bearing.

The there axis accelerometer is based on the Parallax^® Hitachi^® H48C Tri-Axis Accelerometer Module. This module contains a Hitachi H48C module with has 4 analog outputs (3 axes X/Y/Z and 1 temperature) connected to a Microchip^® MCP3204 4 channel 12-bit analog to digital converter.

The two axis magenetic bearing module is based on the Parallax HM55B Compass Module, which in turn is based on the Hitachi HM55B integrated circuit.

2. Programming

Command Name	Bit									Action	Description
	8	7	6	5	4	3	2	1	0
Compass Reset	0	0	0	0	0	0	0	0	0	Send	Reset the A/D converts in the Compass module.
Compass Start	0	0	0	0	0	0	0	0	1	Send	Start the compass measurement:
Compass Status	0	0	0	0	0	0	0	1	0	Send	Return compass module status as ssss. 1100=Done, 0000=In Progress, 1111=Field overflow.
	0	0	0	0	0	s	s	s	s	Receive
X High Get	0	0	0	0	0	0	1	0	0	Send	Return high hyte of X (signed) hhhh hhhh
	0	h	h	h	h	h	h	h	h	Receive
X Low Get	0	0	0	0	0	0	1	0	1	Send	Return low byte of X (signed) llll llll
	0	l	l	l	l	l	l	l	l	Receive
Y High Get	0	0	0	0	0	0	1	1	0	Send	Return high hyte of Y (signed) hhhh hhhh
	0	h	h	h	h	h	h	h	h	Receive
Y Low Get	0	0	0	0	0	0	1	1	1	Send	Return low byte of Y (signed) llll llll
	0	l	l	l	l	l	l	l	l	Receive
Axis Channel High Get	0	0	0	0	0	1	0	c	c	Send	Read 12 bits of channel cc of Axis A/D module and return the high order 4 bits as hhhh. The low 8-bits are latched. For cc, 00=X axis, 01=Y axis, 10=Z axis, 11=VRef.
	0	0	0	0	0	h	h	h	h	Receive
Axis Channel Low Get	0	0	0	0	0	1	1	0	0	Send	Return the low 8-bits of the previous axis channel read as llll llll.
	0	l	l	l	l	l	l	l	l	Receive
Common Commands	0	1	1	1	1	1	1	x	x	Send	Standard common command. See specifications for details.
	0	a	a	a	a	a	a	a	a	Receive
Select	1	a	a	a	a	a	a	a	a	Send	Select the module with an address of aaaa aaaa. A time-out indicates that the module is not selected. (FIXME: 0xa5 is currently returned.)
	0	0	0	0	0	0	0	0	0	Receive

3. Hardware

The hardware consists of a circuit schematic and a printed circuit board.

3.1 Circuit Schematic

The parts list kept in a separate file -- orient5.ptl.

The schematic for the Orient5 module is shown below:

3.2 Printed Circuit Board

The printed circuit board files are listed below:

orient5_back.png

The solder side layer.

orient5_front.png

The component side layer.

orient5_artwork.png

The artwork layer.

orient5.gbl

The RS-274X "Gerber" back (solder side) layer.

orient5.gtl

The RS-274X "Gerber" top (component side) layer.

orient5.gal

The RS-274X "Gerber" artwork layer.

orient5.gml

The RS-274X "Gerber" mask layer.

orient5.drl

The "Excellon" NC drill file.

orient5.tol

The "Excellon" tool rack file.

3.3 Module Insertion

Unfortunately, it is possible to insert the two Parallax modules up-side down. Doing so will invert the power and ground to the chips and possible irreparable damage to the modules. Thus, it is very important to plug the modules into the Orient5 board correctly.

Orient the the Orient5 board such that the black 2×5 RoboBricks2 bus connector on the upper left corner. The U4 3-axis acceleration module connectors will be on the lower left and the U3 2-axis magnetometer module connectors will be on the lower right.

3-Axis Accelleration Module

The 3-Axis Acceleration module has a white dot on its top surface. This white dot is closest to pin 1. Orient the white dot so that it is in the upper left. (I.e. pin 1 is on the top left.)

2-Axis Magentometer Module

The 2-axis magentometer module has a 1 with a circle around it on the bottom of the board. This mark is closest to pin 1. Orient pin 1 so that it is towards the upper left.

4. Software

The following files are available:

orient5.ucl

The Orient5 µCL source code file.

orient5.asm

The Orient5 firmware assembly code listing.

orient5.lst

The Orient5 firmware listing file.

orient5.hex

The Orient5 firmware Intel^® Hex file.

5. Issues

The following fabrication issues occured:

• U4 can be moved .05 inch to the right.
• U3 can be moved .05 inch to the left.
• The current profile for the compass chip is pretty nasty as shown below:

  

  A redesign to opto isolate the chip may be necessary. Those 45mA spikes are pretty nasty looking.