MEEPS - Modular Embedded Experimenter's PIC System

Rev'd for ECPE 5, 2004
J. Dunmire

Introduction

MEEPS is a PCB designed for use in several classes taught by Dr. Richard Turpin at the UOP School of Engineering and Computer Science . MEEPS is an expansion of the ECPE-5 - PIC Project Board that includes improvements learned from using the PIC Project Board along with new daughter boards.

Update - February 2004

A variation of MEEPS has been completed for the Spring 2004 ECPE 5 class at UOP. This variation consists of just the CPU and Display sections. The requirements for this variation are derived from the requirements below.

Requirements

MEEPS will have four (4) sections:

CPU

The CPU section is similar to the CPU section of the PIC Project Board . The requirements are stated in terms of differences from the PIC Project Board:
  1. CPU shall be a PIC18F452 instead of the PIC16F877. These two PIC processors are pin compatible, but the boot monitor and serial interface are being changed to be compatible with the QuikBug monitor .
  2. The linear regulator, bridge, and associated components will be removed. Board power will be provided by an external regulated power source. The nominal input voltage requirements will be 2-5 volts DC. Note that the components on some daughter boards may require a minimum voltage greater than 2 volts (in particular, the accelerometer on the Sensor and Control board requires a minimum of 3 volts DC.)
    The board shall be protected from the application of reverse voltages through the use of a shorting diode and a PTC Thermistor.
  3. Mounting holes will be added.
  4. The 10 pin SIP programming connector shall be replace with a 6 contact modular connector to mate with the Microchip MPLAB ICD 2 in-circuit debugger.
  5. Connect the RS-232 interface to the UART on the 18F452.
  6. Add a series resistor to the reset (MCLR\) line as recommend by the PIC data sheets to protect against latch-up.
  7. Add a power switch.
  8. Increase the space between the PIC processor and the 40-pin expansion connector so that the pins on the PIC processor can be probed when a header is installed.
  9. Add a test pin for grounding probes.
  10. Reduce the current to the LEDS.
  11. Replace the MAX232 with a low voltage (2 volt) part.
  12. Add solder pads to the mounting holes for the 9-pin connector. Connect the tabs to ground.

Display and Basic I/O

This section is similar to the daughter board section of the PIC Project Board . The requirements are stated in terms of differences from the PIC Project Board:
  1. Add mounting holes.
  2. Drop the large dot-matrix LED display.
  3. Consider replacing the individual resistors with a SIP or DIP package to reduce the assembly effort.
  4. Enlarge the TO-92 mounting pattern to ease assembly.
  5. (optional) Add a second 1-Wire device and a connector for of-board expansion on the 1-Wire bus.
  6. (optional) Add ADXL202 Accelerometer.

Sensor and Control Board

This new daughter board will have sensors, power drive outputs and communications interfaces. Where possible, these will be through hole versions of the same components on the Remote Sensor and Control board. This daughter board will not be wired directly to the CPU board. To use this board section, it will be necessary to cut the MEEPS into sections and use the 40 pin headers, or use 40 pin headers and ribbon cables to connect this section to the CPU.

There will be a number of variations possible on this board and not all components can be installed at the same time.

Requirements for the Sensor and Control Board:
  1. Same size as the Display daughter board.
  2. Same mounting holes as the Display daughter board.
  3. 40 pin CPU connector.
  4. ADXL202 dual axis accelerometer.
  5. IrDA interface with the following components. Note: The TIR1000 and the MCP2150 can not be used at the same time.
  6. 433 MHz Transmitter (two options)
  7. 433 MHz Receiver (two options)
  8. SHT71 Humidity and Temperature Sensor (from Sensirion)
  9. Four MOSFET outputs that can be used as individual outputs, two (2) half-bridges, or a single full-bridge. Minimum 12v drain-source voltage.
  10. MOSFET outputs and uncommitted I/O signals from the CPU section shall be available on a header or connector separate from the 40-pin CPU header.
  11. (Optional, depending on space available) A 0.100x0.100 grid of plated holes for prototype circuits.

Remote Sensor and Control

The Remote Sensor and Control section of MEEPS is envisioned as a standalone module that, depending on configuration, will provide remote sensing and/or control with RF or IR communications. The Remote Sensor and Control section will use surface mount components, where available and reasonable, to reduce the size of the module. Two CPU options will be provided. This module will be designed for battery operation.
  1. Microchip PIC12F629/675 Microcontroller
  2. Microchip PIC18F1220/1320 Microcontroller
  3. A 6 contact modular connector to mate with the Microchip MPLAB ICD 2 in-circuit debugger.
  4. A single cell AA battery holder
  5. DC-DC converter to boost battery voltage to 3.3v.
  6. ADXL202 dual axis accelerometer.
  7. IrDA interface with the following components. Note: The TIR1000 and the MCP2150 can not be used at the same time.
  8. 433 MHz Transmitter (two options)
  9. 433 MHz Receiver (two options)
  10. SHT71 Humidity and Temperature Sensor (from Sensirion)
  11. Four MOSFET outputs that can be used as individual outputs, two (2) half-bridges, or a single full-bridge. Minimum 12v drain-source voltage.
  12. A 1-Wire memory device and expansion port for off board devices.
  13. MOSFET outputs, uncommitted I/O signals from the 18F1220/1320 microcontroller, and 1-wire expansion port shall be available on a header or connector.
Note: It I/O devices on this board will be connected to the on board processors. Only a subset of the devices will be connected to the 12F629/675.
$Date: 2008-10-21 19:17:34 $
$Revision: 1.4 $
$Source: /home/cvsroot/MEEPSTop/MEEPS.html,v $ 		Contact me by email: jedunmire at gmail.com