DT101 PIC SimmStick CPU Board



Features

  • PIC 16F84 or 16Cxx Single-chip microcontroller.
  • RS232 Communications Port using a Max-232.
  • Brown-out detector
  • Real Time clock using a DS-1202/1302 or Panasonic NJU-6355,
  • ADC  which supports most of the popular 8 pin devices
    (eg. LTC1298 12 bit A/D or National ADC0831 8 bit)
  • 2K to 64K serial 24LCxx type EEPROM.

A PicStic equivalent on a SimmStick, on a 1.05" x 3.5" double-sided plated-through solder-masked Silk Screened 1.26mm thick Printed circuit Board.

It supports any 18 pin PIC16Cxx Micro and it will cater for the FED Interpreter Basic and the microEngineering Labs PicBasic compiler.

DT101 Circuit - click here

DT101 Datasheet - in PDF - click here

Component Overlay

DT101 overlay.gif

Parts List

1 x DT101 PCB 
1 x 780L5 +5V regulator in TO-92 case (Optional)
1 x Capacitor C1 .01uf (or .1uf) Ceramic
1 x Capacitor C2 .01uf (or .1uf) Ceramic
1 x Capacitor C3 15pf to 22pf Ceramic       
Install C3 & C4 only if Crystal is installed
1 x Capacitor C3 15pf to 22pf Ceramic
1 x Capacitor C4 15pf to 22pf Ceramic
1 x Resistor  R1 10K .25 watt
1 x Resistor  R2 10K .25 watt
1 x Resistor  R3 10K .25 watt
R1, R2, and R3 must always be installed, even 
if you don't use a brown-out circuit.       
(Install R4 & R5 only if EEPROM is installed)
1 x Resistor  R4 10K .25 watt   
1 x Resistor  R5 10K .25 watt         
1 x Crystal - include C3 and C4
 OR
1 x 3 pin Resonator - omit C3 & C4

The most common crystal used for beginners is 4Mhz, as this matches the PIC16C84/04/P.

Assembly Options

Serial Communications

All caps (C5-C8) are Electrolytic/Tant. 16V-PCB mount
1 x Capacitor C5 1uf 
1 x Capacitor C6 1uf 
1 x Capacitor C7 1uf 
1 x Capacitor C8 1uf 
1 x MAX-232 E2 (or equivalent)

It may also pay to install a 16 pin socket for the Max-232, as you may have to remove it for some configurations.

Real Time Clock:

The Panasonic NJU-6355 requires a crystal with a load capacitance of 12pf.
The Dallas units need a 6pf crystal. I have both of these 32.768khz crystals in stock.
Sample code can be found at http://www.dontronics.com/rtc.html.

Analog to Digital Converter

Most common A/D chips will fit this 8 pin DIP layout. Although the original PicStic used an LTC1298, a simple National ADC0831 will fit the same socket.

Sample code for both the NJU-6355 RTC and LTC-1298 A/D can be found at Micromint's PicStic(tm) site at http://www.micromint.com/modules.htm This has Circuits, Overlays, Code, Data Sheets for the 1, 2, and 3 PicStic.
Beware, they keep changing this site to different URL's.

Brown-Out Circuit

This small TO-92 IC is used to prevent the Micro operation becoming unpredictable during a power 'brown-out'. In most cases this isn't required. It's just an added precaution for reliable operation. The older PIC16C5x may well need this device.

To use the brown-out detector, just add it to the board, and can be either a CMOS or Open Collector type.

You can use the following brownout detector ICs:

  • Panasonic MN13811-S (Open Collector)

  • Panasonic MN1381-S (CMOS)

  • Zetek ZM33064

  • Motorola MC33064P

Other types may also be suitable. For 5V operation, they should switch between 4.2 and 4.6 Volts.

R1, R2, and R3 MUST BE INSTALLED for normal operation.
(even if you don't use a brown-out circuit)

By simply ignoring the brown-out circuit and installing resistors R1 and R2, circuit operation should be fine.

Pin-out Headers

J1:  Isolate the 78L05 Regulator from SimmStick +5V
Used to Isolate the +5V signal on the edge connector from the 78L05 regulator output if it is installed. Both outputs should never be used together. The track on the solder side of the board under J1 needs to be cut to isolate the 78L05 regulator output. A test link and two male posts are used to reinstall the regulator output.
 
J2:  Brings in an alternative source of DC power.
A 9 Volt battery may be connected to J2. Pin 1 is positive and pin 2 negative.
 
J3:  ADC Control Inputs
You may connect your A/D chip signals here. Care must be taken to make sure there are no hardware conflicts. Sure you can use the same pinout as the PicStic, but this would mean your Max-232 Comms, and EEPROM may need to be re-mapped.
 
J4: The Real Time Clock control lines.
      As above, be sure you don't conflict with other signals.
J5: ADC - Analog to Digital Converter Input lines.
J6: Backup Battery input to Dallas DS-1302 to VCC2
J7: Connection points for 3V Coin Type watch or hearing aid battery.

Board Modifications

Users who want to access an EEPROM on the DT101 PCB's using the MEL complier need to edit the PIC.PBL file to reverse the Pin allocation for the I2C function (SDA & SDL). from Wolf Maier SCORPIA DESIGN 4-Sep-98.

DT101 CPU Board + Prototype Area - DT111

The DT111 is simply the DT101 Simmstick with an extra 1" of prototype area. The schematic and overlay are the same except for this additional 1 inch of prototype area. The prototyping area can be used to connect the Basic Stamp One 93LCxx type EEPROM.