Crossover Connections; Jtag Connector; Pickit 2 Connector - Microchip Technology Explorer 16 User Manual

4.2.14
Connector J14 provides the footprint for a 6-pin PICkit 2 programmer interface. This will
provide a third low-cost programming option, besides MPLAB ICD 2 and the JTAG
interface, when PICkit 2 support for larger devices become available in the future.
4.2.15
Connector J13 provides a standard JTAG interface, allowing users to connect to and
program the controller via JTAG.
4.2.16
The Explorer 16 board has been designed with the PICtail™ Plus modular expansion
interface, allowing the board to provide basic generic functionality and still be easily
extendable to new technologies as they become available.
PICtail Plus is based on a 120-pin connection divided into three sections of 30 pins,
30 pins and 56 pins. The two 30-pin connections have parallel functionality; for exam-
ple, pins 1, 3, 5 and 7 have SPI1 functionality on the top 30-pin segment, with similar
SPI2 functionality on the corresponding pins in the middle 30-pin segment.
Each 30-pin section provides connections to all of the serial communications
peripherals, as well as many I/O ports, external interrupts and A/D channels. This pro-
vides enough signals to develop many different expansion interfaces, such as
Ethernet, Zigbee™, IrDA
used in either the top or middle 30-pin sections.
The Explorer 16 board provides footprints for two edge connectors for daughter cards,
one populated (J5, Samtec # MEC1-160-02-S-D-A) and one unpopulated (J6). The
board also has a matching male edge connection (J9), allowing it to be used as an
expansion card itself.
4.2.16.1
The PICtail Plus interface allows two Explorer 16 boards to be connected directly to
each other without any external connector. This provides 1-to-1 connection between
the microcontrollers on the two boards, an interface that works well for many types of
peripherals (I
and UARTs, require cross-wire connections; that is, the TX (or SDO) pin of one
controller must be connected to the RX (or SDI) of the other and vice versa.
The Explorer 16 board uses two 74HCT4053 analog multiplexers to simplify the con-
nections between itself and any daughter boards. U6 and U7 provide active control of
the cross-wire capability on SPI1 and UART1, with a hardware flow control signal
provided by three I/O pins.
The multiplexers are controlled by the state of pins RB12, RB13 and RB14. When a
control pin is high (the default state), the corresponding SPI1 or UART1 pin pairs are
connected to their default pins on the PICtail Plus interface. When a control pin is
asserted low, the corresponding pin pair functions are swapped. Table 4-1 details the
relationship between the control pins and SPI1/UART1 functions on the interface.
© 2005 Microchip Technology Inc.
Explorer 16 Development Hardware

PICkit 2 Connector

JTAG Connector

PICtail™ Plus Card Edge Modular Expansion Connectors
®
and so on. The 30-pin PICtail Plus expansion boards can be
CROSSOVER CONNECTIONS FOR SPI AND UART
2
C, PMP, etc.). However, certain serial peripheral modules, such as SPIs
DS51589A-page 30