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Digilent chipKIT Network Shield에 대해서도 마찬가지입니다: 참조 매뉴얼 및 사용자 가이드 (11 페이지)

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chipKIT™ Network Shield™ Reference Manual

Jumper JP4 on the Network Shield is used to route power to the host connector being used. Place the shorting

block in the "A" position when using the standard USB type-A (host) connector J4. Place the shorting block in the

"MICRO" position for use with the USB micro-AB (OTG) connector J2.

When operating as a USB host, the PIC32MX795 microcontroller controls application of power to the connected

device via the VBUSON control pin (labeled VBUSON in the schematic). Bus power is applied to the USB bus by

driving the VBUSON pin high. Power is removed from the bus by driving the VBUSON pin low. The VBUSON pin is

accessed via bit 3 of the U1OTGCON register. The VBUSON signal is shared with same microcontroller pin as analog

input A5 and digital pin 59.

The VBUSON pin drives the enable input of a TPS2051B current-limited power distribution switch to control the

application of USB power to the host connector. This switch has over-current detection capability and provides an

over-current fault indication by pulling the signal USBOC low. The over-current output pin can be monitored via

the INT1/RE8 pin on the PIC32MX795 microcontroller. This signal appears on connector J14, pin 5 on the Max32

board, and chipKIT digital pin 2. Details about the TPS2051B are available from the data sheet at the Texas

Instruments web site.

The VBUSON signal is shared with the same microcontroller pin as analog input A5 and digital pin 59. This pin is not

available for other uses when operating as a USB host. If the Max32/Network Shield is not being used as a USB

host, you can use A5/pin 59 by cutting the trace on the bottom of JP3. USB host capability can be restored by

soldering a 2-pin header to JP3 and installing a shorting block.

The PIC32 USB controller can be accessed using the chipKIT USB libraries for use within the MPIDE environment.

When using the Max32/Network Shield outside the MPIDE environment, the Microchip Application Library

provides USB stack code that can be used with the Max32/Network Shield. There are reference designs available

on the Microchip web site demonstrating both device and host operation of PIC32 microcontrollers. These

reference designs are suitable for developing USB firmware for the Max32/Network Shield.

2.3

CAN Interface

The Controller Area Network (CAN) is a control networking standard originally developed for use in automotive

systems, but has since become a standard used in various industrial control and building automation networking

applications as well.

The PIC32MX795 microcontroller on the Max32 contains two independent CAN network controllers. These CAN

controllers in combination with two Microchip MCP2551 CAN transceivers on the Network Shield allow the

Max32/Network Shield to operate on one or two independent CAN networks.

When not using the MPIDE environment, refer to the PIC32MX7XX data sheet, the PIC32 Family Reference Manual,

and the CAN network documentation available at www.microchip.com for information on CAN controllers and

CAN networking in general.

The PIC32MX795 microcontroller provides two sets of pins that can be used to connect the CAN controllers to the

external transceivers. The Max32/Network Shield is designed to use the alternate (not the standard) pins. This

selection is made using the configuration variables in the microcontroller, set using a #pragma config

statement. To select the use of the alternate interface pins, the following statement must appear in the main

program module:

#pragma config FCANIO=OFF

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