Vault 7: Projects
This publication series is about specific projects related to the Vault 7 main publication.
1.5.4 PIC18F46J50 Plug-In-Module (PIM)
The PIC18F46J50 PIM services as a development platform for the PIC18F46J50 family. It includes 2 LEDs and a push
button. It can also optionally be connected to the PIC18 Explorer board for access to additional features, such as
potentiometer, PICtail, temperature sensor, etc.
Description
Overview
• JP2 - This is a three-pin header with the labels, "I", "R" and "U". The "R" is an abbreviation referring to microcontroller pin,
RC2. "I" is an abbreviation referring to the "ICE" female header pin for the RC2 signal. "U" is an abbreviation for the USB
VBUS line. When the jumper is in the "R" to "I" position, the RC2 pin connects only to the ICE female header pin, just like
most of the other general purpose I/O pins. When the jumper is in the "R" to "U" position, RC2 (which is 5.5V tolerant) can
be used to sense when the USB cable has been attached to the host, and when the host is actively providing power to the
+5V VBUS line. According to the USB 2.0 specifications, no device should ever pull the D+ or D- lines high (such as with
the D+ or D- pull-up resistor) until the host actively powers the +5V VBUS line. This is intended to prevent self-powered
peripherals from ever sourcing even small amounts of power to the host when the host is not powered. Small amounts of
current could potentially prevent the host (and possibly other USB peripherals connected to that host) from fully becoming
depowered, which may cause problems during power-up and initialization. Self-powered peripherals should periodically
monitor the +5V VBUS line and detect when it is driven high. Only when it is powered should user firmware enable the
USB module and turn on the D+ (for full speed) or D- (for low speed) pull-up resistor, signaling device attach to the host.
The recommended method of monitoring the +5V VBUS line is to connect it to one of the microcontroller.s 5.5V tolerant
I/O pins through a large value resistor (such as 100 kOhms). The resistor serves to improve the ESD ruggedness of the
circuit as well as to prevent microcontroller damage if user firmware should ever unintentionally configure the I/O pin as
an output. Peripherals which are purely bus powered obtain all of their power directly from the +5V VBUS line itself. For
these types of devices, it is unnecessary to monitor when the VBUS is powered, as the peripheral will not be able to
source current on the D+, D- or VBUS lines when the host is not powered.
• JP3 - This jumper is located in series with the +5V VBUS power supply line from the USB connector. When the jumper is
removed, a current meter may be placed between the header pins to measure the board current which is being drawn
from the USB port. Additionally, by removing the jumper cap altogether, JP3 provides a means of preventing the board
from consuming USB power.
• S2 - Switch for application use. Tied to RB2.
• S4 - MCLR reset switch
• D1 - LED for application use. Tied to RE0.
• D2 - LED for application use. Tied to RE1.
More Information
Product webpage
1.5 Demo Board Information MLA - USB Library Help PIC18F47J53 Plug-In-Module (PIM)
224
Protego_Release_01_05-Related-OEM-Documentation-MLA_v2013_12_20-help_mla_usb.pdf