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Main Board

by Sébastien Lelong last modified 2008-06-04 20:40
Author: Sébastien Lelong, The SirBot Project, 2005
Revision History
Revision: 409 Initial creation
Revision: 441 Convert to REST
$Revision: 538 $ include 16F88: changed doc and diagrams
Abtract

The Main Board is the central electronic board of the SirBot Project. It contains a microcontroller which permits to control every SirBot Modules (external boards).

The version of this board has a integrated RS232 module for communication capabilities via the serial port.

Currently, two microcontrollers can be used, with minor modifications in the assembly: PIC 1F628 and PIC 16F88. This only difference is about connecting the UART module. PIC 16F88 is a better choice, as it has more memory, ADC (analog-to-digital) and mostly it can be programmed using a bootloader (such as TinyBootloader, fully tested, see python version pytbl.py in the 3rd party SirBot distrib).

Electronic diagram

The Main Board corresponds to the following diagram (here for a 16F628):

main_board.jpg

For the RS232 module, we have the following diagram:

RS232.jpg

Microcontrollers pin diagrams

The following pictures show pin diagrams for 16F628 and 16F88 microcontrollers, with differences about UART pins.

16F88.jpg
16F628.jpg

Main Board components

Components list
Name Value Picture
R1, R2 Resistances 1
R_1K.jpg
C1 Condenser 10µF
C_100uF.jpg
C2 Condenser 100nF
C_100nF.jpg
C3, C4 Condenser 22pF
C_22pF.jpg
C5, ..., C9 Condenser 1µF
C_1mF.jpg
D Diode 1N4001 or 1N4004
D_1N4001.jpg
L1 Led
Led_Red.jpg
Q Quartz 20MHz (or 4/10 Mhz, preferably 20MHz)
Q_4MHz.jpg
REG Voltage regulator 7805
7805.jpg
CI1 Microchip PIC 16F628 or PIC 16F88
PIC_16F628.jpg
CI MAX232 MAX232
MAX232.jpg
J Power supply connector 2.5mm
PS_jack.jpg
K 26 pins connector
Connector_26pins.jpg
K2 RS232 connector (male)
Connector_RS232.jpg
Note:This board needs a (at least) 9V/500mA power supply, not regulated (there is a voltage regulator on the board).

Connection specifications

The Main Board provides a bus connection (via connector K). Every external modules have this connector so they can be plugged-in and controlled by the Main Board. hus, this bus provides communication capabilities between every boards and must respect the following specifications:

  • The connector has 26 pins.
  • 18 pins are used to have access to every pin of the PIC 16F628
  • 2 pins are used to provide power supply to other modules.
  • So, 6 pins aren't used yet

The connection diagram is the following:

../buscable/Bus_spec.jpg

Electronic assembly

The following pictures show the implementation of the components on a board (with holes) and the reverse side of the board. Layout differences are shown in red whether 16F88 or 16F628 is used.

mainboard_components_16F88.jpg
mainboard_components_16F628.jpg

The reverse side is the same:

mainboard.jpg

Results

mainboard_up.jpg

Component view of the main board

mainboard_down.jpg

Reverse view of the main board

rs232_detail.jpg

Details of RS232 straps

Quartz_support.jpg

Support for the quartz

mainboard_face.jpg

Front view with connections

mainboard_facade.jpg

Facade view

connector_cable.jpg

Connector with bus cable

mainboard_ov.jpg

Complete overview

Tests

TODO...


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