View source for PHCC Motherboard

= The PIC HomeCockpit Controller (PHCC) Motherboard  =

== Description  ==

The PHCC motherboard is the core component of the PHCC system. It connects to the computer via serial port (RS-232) or via USB. 

A PIC18F452 microcontroller is used as the "heart" of PHCC. It is responsible for communicating with the PC via a simple protocol and it scans the Analog inputs as well as the keymatrix every few milliseconds. 

The motherboard houses the following subsystems: 

*35 analog inputs (3 priority, 32 normal) in form of a pinheader with 3 terminals for each analog input 
*16 connectors for 16 keymatrix daughterboards (64 inputs per board). For IDC flat ribbon cables. 
*a RS-232 serial port (for Null Modem cables) with level converter (MAX232) 
*a socket for USB interface board 
*an I2C port 
*a connector for Output daughterboards of "Type A" (DOA) using a 2x5 pinheader for IDC flat ribbon cables. 
*and a connector for output daughterboards of "Type B" (DOB) using a 2x5 pinheader for IDC flat ribbon cables.

== Schematic and Layout  ==

Current revision (Rev.4B) of the motherboard (Sept 28th 2004): 

[[Image:PHCC_motherboard_sch_rev4b.png|thumb|center|500px|Rev.4B Schematic]]<BR>
[[Image:PHCC_motherboard_brd_rev4b.png|thumb|center|500px|Rev.4B Layout]]

Revision 4 schematic and layout (Aug 16th 2004): 

[[Image:PHCC_motherboard_sch_rev4.png|thumb|center|500px|Rev.4 Schematic]]<BR>
[[Image:PHCC_motherboard_brd_rev4.png|thumb|center|500px|Rev.4 Layout]]

== Assembly Instructions  ==

work in progress, pictures to accompany descriptions soon. 

*text only, Rev.4: [http://cockpit.varxec.net/electronics/phcc/tutorials/Motherboard_Rev4_assembly_tutorial.txt Motherboard_Rev4_assembly_tutorial.txt] 
*text only, Rev.4B: [http://cockpit.varxec.net/electronics/phcc/tutorials/Motherboard_Rev4b_assembly_tutorial.txt Motherboard_Rev4b_assembly_tutorial.txt]

== Download  ==

See [http://cockpit.varxec.net/electronics/phcc/download.html download page] 

'''Note about Resistors:''' all resitors are standard kind, ie. 1/4W, carbon film, +/-10% (Its generally a good idea to get lots of 10k and 330R resistors. the 10k are for pullups, the 330R for LEDs) 

== Board Errata  ==

The Rev.4 boards as sent to the boardhouse have a tiny mistake:<br> The numbering of the capacitors skips C8/9. 

== Changes between Revisions:  ==

{| cellpadding="5" class="plain"
|-
| valign="top" | Rev.4B 
| No functional changes. Added two Capacitors, one electrolytic for the incoming power supply, the other as a blocking cap, serving the second set of supply pins of the PIC.
|-
| valign="top" | &nbsp; 
| Improved spacing between the KEY1-KEY16 connectors.
|-
| valign="top" | &nbsp; 
| Moved blocking caps of the 4067's to be nearer the supply pins.
|-
| valign="top" | &nbsp; 
| Narrowed the capacitor lead pitch of the MAX232's caps.
|-
| valign="top" | &nbsp; 
| Gave the resistors a bit more space.
|-
| valign="top" | &nbsp; 
| Put in markings for LED polarity.
|-
| valign="top" | &nbsp; 
| Standardized Mounting hole positions.
|-
| valign="top" | Rev.4 
| Had to change pins used for analog inputs since microcontroller allows only consecutive ADC pins to be used. You have to start with AN0. (Lesson learned: always read the datasheet first&nbsp;:-)
|-
| valign="top" | &nbsp; 
| Added and beautified text and markings on component print (makes it look 'prettier'"&nbsp;:-)
|-
| valign="top" | &nbsp; 
| More space between pinheaders for DOA and DOB
|-
| valign="top" | &nbsp; 
| Fixed Debug LEDs. With Rev.3, only one of the two LEDs worked because of a thinking error.
|-
| valign="top" | &nbsp; 
| The 74HC/HCT154 is available in two formats, DIL24 and DIL24 narrow, now the board will accept both formats
|-
| valign="top" | &nbsp; 
| Reversed lines for lower nibble of PortB that control the 74HCT154. This makes the firmware easier. Old Rev.3 wiring is still supported in firmware via #ifdefs
|-
| valign="top" | Rev.3 
| aka. "The Prototype"
|-
| valign="top" | &nbsp; 
| First finished and prototyped board. Had to manually correct the ANx inputs(see Rev.4)
|-
| valign="top" | Rev.2 
| rowspan="3" | These were never finished/fully routed boards. They were results of tests of either trials of how to run the traces or with different chips.
|-
| valign="top" | Rev.1
|-
| valign="top" | Rev.0
|}