Vault 7: Projects
This publication series is about specific projects related to the Vault 7 main publication.
dsPIC33/PIC24 Family Reference Manual
DS70000195F-page 64 2007-2014 Microchip Technology Inc.
12.0 CONSTANT-CURRENT SOURCE
The constant-current source module is a precision current generator and is used in conjunction
with an Analog-to-Digital Converter (ADC) to measure the resistance of external resistors
connected to device pins. A typical use of this peripheral is to set the I
2
C board address using
resistors, as explained in the following sections.
12.1 Features Overview
The constant-current source module offers the following major features:
• Constant-current generator (10 µA nominal)
• Internal selectable connection to one out of four pins
• Enable/Disable bit
12.2 Module Description
Figure 12-1 shows a functional block diagram of the constant-current source module. It consists
of a precision current generator, with a nominal value of 10 µA. The module can be enabled and
disabled using the ISRCEN bit (ISRCCON<15>). The output of the current generator is
internally connected to one out of four pins. The OUTSEL<2:0> bits (ISRCCON<10:8>) allow
selection of the target pin. The current source is calibrated during testing. The calibration value
is stored into the Flash die serialization area, and should be read and transferred to the
ISRCCON register by the application firmware, before using the peripheral.
Figure 12-1: Constant-Current Source Module Block Diagram
Note: The constant-current source module is not available on all devices. Refer to the
specific device data sheet for availability.
ISRC1
ISRC3
M
U
X
OUTSEL<2:0>
ISRC2
ISRC4
ISRCEN
Constant-Current Source
Protego_Release_01_05-Related-OEM-Documentation-PIC24FJ32MC10X-Reference_Manual-PIC24FJ32MC102-I2C.pdf