This is the Revision A verion of the Digital8 module. The status of this project is finished.

Digital8 Module (Revision C)

Table of Contents

This document is also available in PDF format.

1. Introduction

The Digital8 module provides the ability to input and output 8 bits of digital data. The direction of each bit can be changed under program control.

2. Programming

The programmer can download a complement mask to cause any of the bits to be complemented prior to reading.

The Digital8 module supports the Interrupt Protocol. The interrupt pending bit is set whenever the the formula:

L&(~I) | H&I | R&(~P)&I | F&P&(~I)]
is non-zero, where: and Once the interrupt pending bit is set, it must be explicitly cleared by the user.

The Digital8 module supports both the standard shared commands and the shared interrupt commands in addition to the following commands:

Command Send/
Receive
Byte Value Discussion
7 6 5 4 3 2 1 0
Read Inputs Send 0 0 0 0 0 0 0 0 Return 8-bits of input iiii iiii (after XOR'ing with complement mask)
Receive i i i i i i i i
Read Outputs Send 0 0 0 0 0 0 0 1 Return 8-bits of the outputs oooo oooo (after XOR'ing with complement mask.)
Receive o o o o o o o o
Read Complement Mask Send 0 0 0 0 0 0 1 0 Return 8-bits of complement mask cccc cccc
Receive c c c c c c c c
Read Direction Mask Send 0 0 0 0 0 0 1 1 Return 8-bits of direction mask dddd dddd
Receive d d d d d d d d
Read Low Mask Send 0 0 0 0 0 1 0 0 Return 8-bits of low mask llll llll
Receive l l l l l l l l
Read High Mask Send 0 0 0 0 0 1 0 1 Return 8-bits of the high mask hhhh hhhh
Receive h h h h h h h h
Read Rising Mask Send 0 0 0 0 0 1 1 0 Return 8-bits of the rising mask rrrr rrrr
Receive r r r r r r r r
Read Falling Mask Send 0 0 0 0 0 1 1 1 Return 8-bits of the falling mask ffff ffff
Receive f f f f f f f f
Read Raw Send 0 0 0 0 1 0 0 0 Return 8-bits of raw input data rrrr rrrr (without XOR'ing with complement mask)
Receive r r r r r r r r
Reset Outputs Send 0 0 0 1 0 0 0 0 Set all 8 bits of outputs to 0 (then XOR with complement mask).
Set Outputs Send 0 0 0 1 0 0 0 1 Set output bits to oooo oooo.
Send o o o o o o o o
Set Complement Mask Send 0 0 0 1 0 0 1 0 Set 8-bits of complement mask to cccc cccc
Send c c c c c c c c
Set Direction Mask Send 0 0 0 1 0 0 1 1 Set 8-bits of direction mask to dddd dddd 1=input; 0=output
Send d d d d d d d d
Set Low Mask Send 0 0 0 1 0 1 0 0 Set 8-bits of low mask to llll llll
Send l l l l l l l l
Set High Mask Send 0 0 0 1 0 1 0 1 Set 8-bits of the high mask to hhhh hhhh
Send h h h h h h h h
Set Rising Mask Send 0 0 0 1 0 1 1 0 Set 8-bits of the rising mask to rrrr rrrr
Send r r r r r r r r
Set Falling Mask Send 0 0 0 1 0 1 1 1 Set 8-bits of the falling mask to ffff ffff
Send f f f f f f f f
Set Outputs Raw Send 0 0 0 1 1 0 0 0 Set 8-bits to oooo oooo with no complement mask.
Send o o o o o o o o
Reset Everything Send 0 0 0 1 1 0 0 1 Reset all registers to 0 and set direction bits to 1 (input)
Set Output Bit Send 0 0 1 0 v b b b Set output bit bbbb to v
Set Outputs Low Send 0 1 0 0 l l l l Set low order 4-bits of Outputs to llll and then XOR complement mask
Set Outputs High Send 0 1 0 1 h h h h Set high order 4-bits of Outputs to hhhh and and then XOR complement mask
Set Direction Low Send 0 1 1 0 l l l l Set low order 4-bits of direction to llll.
Set Direction High Send 0 1 1 1 h h h h Set high order 4-bits of direction to hhhh.
Set Interrupt Commands Send 1 1 1 1 0 c c c Set Interrupt Command ccc.
Shared Commands Send 1 1 1 1 1 c c c Execute Shared Command ccc

3. Hardware

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

3.1 Circuit Schematic

The schematic for the Digital8 module is shown below:

Digital8 Schematic

The parts list kept in a separate file -- digital8.ptl.

3.2 Printed Circuit Board

The printed circuit files are listed below:

digital8_back.png
The solder side layer.
digital8_front.png
The component side layer.
digital8_artwork.png
The artwork layer.
digital8.gbl
The RS-274X "Gerber" back (solder side) layer.
digital8.gtl
The RS-274X "Gerber" top (component side) layer.
digital8.gal
The RS-274X "Gerber" artwork layer.
digital8.drl
The "Excellon" NC drill file.
digital8.tol
The "Excellon" tool rack file.

3.3 Construction Instructions

The construction Instructions are located in a separate file to be a little more printer friendly.

4. Software

The Digital8 software is available as one of:

digital8.ucl
The µCL source file.
digital8.asm
The resulting human readable PIC assembly file.
digital8.lst
The resulting human readable PIC listing file.
digital8.hex
The resulting Intel® Hex file.

5. Issues

Any fabrication issues will be listed here.


Copyright (c) 2001-2005 by Wayne C. Gramlich. All rights reserved.