Digilent 6021-210-000P-KIT - Manual (Page 8)

Universal Development Board™ Reference Manual
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Page 8 of 27
The PICtail™ Plus bus is based on a 120-pin connection divided into three sections of 30pins, 30pins and 56pins.
The two 30-pin connections have parallel functionality. Each 30 pin section provides connections to all of the serial
communications peripherals, as well as I/O port. This functionality provides enough signals to develop many
different expansion interfaces.
In addition to the microcontroller signals, the PICtail™ Plus bus has pins defined for three power supply voltages
and ground. The pins labeled as 3V3 are powered from the main 3.3V power supply on the UDB board. The pins
labeled as 5V0 are powered directly from the power supply source selected by the power select jumper J21. These
pins will only be at 5.0V if the power supply used to power the board is a regulated 5V supply or USB. The pins
labeled as 9V0 are powered from a power supply attached to header J5 in the upper right corner of the board.
Header J5 is used to bring in an externally regulated 9V power supply to those pins.
4.1 PIM Bus
The PICtail™ Plus connectors are connected to the PIM Socket what is called the PIM bus. There are hard wired
connections between the pins of the PIM Socket (and the on-board PIC32 microcontroller) and the pins of the
PICtail™ Plus connectors. It is not necessary to use jumper wires to make connections between PIMs (or the on-
board PIC32 microcontroller) and PICtail™ Plus modules connected to the PICtail™ connectors. The connections
between the PIM connector and the PICtail™ connectors are the same as on a Microchip® Explorer 16 board.
Access to the signals on the PIM bus can be accomplished using the pin header connectors labeled PIM Headers on
the board. These headers: J9, J10, and J11, provide access to all microcontroller signals going between the PIM
Socket and the PICtail™ connectors. Connectors J9 and J10 are 40-pin headers, and J11 is a 16 pin header. These
are standard 100mil spaced pin header connectors compatible with MTE style connectors.
These connectors can be used to monitor the signals between the microcontroller and the peripheral for
debugging purposes when using a PIM or the on-board PIC32MX360 microcontroller. They can also be used to
establish connections to the PICtail™ Plus signals when using a microcontroller in one of the DIP sockets. In this
case, MTE jumper wires would be used to make the connections between the DIP bus and the PIM bus.
Refer to Appendix A: PICtail™ Plus/PIM Bus Connections for a table showing the correspondences between pin
numbers and signal assignments for the PICtail™ Bus the PIM Bus and the PIM Headers.
5 DIP Sockets
The UDB has 3 DIP sockets at locations IC2, IC3, and IC4. These sockets are for 20/14/8-pin 8-Bit PIC, 28-pin
PIC24/dsPIC33/PIC32, and 28-pin 8-Bit PIC devices respectively. The board is labeled to reflect this next to each
socket. The labeling for IC3 doesn’t mention PIC32, but the board is fully compatible with PIC32MX devices in DIP
packages. Generally, only one of these sockets should be used at a time, as all three DIP sockets are wired in
parallel and having multiple devices installed simultaneously will cause conflicts between the I/O pins on the
various devices.
The pins from the three DIP sockets are wired in parallel and make up the DIP bus. This bus is wired to the DIP Bus
header, and jumper wires can be used to jumper signals from the DIP bus header to other locations on the board,
such as the user I/O buttons/LEDs or to off board devices.
Although the IC2 socket is a 20-pin socket, smaller pin count DIP devices may be used. When installing a smaller
pin count device, such as an 8-pin DIP device into the 20-pin DIP socket, load the device such that pin 1 on the
microcontroller is inserted into pin 1 on the socket, i.e. the devices are loaded at the upper end of the socket.