PIC32MX795F512L-80IPT Datasheet, PDF (13/68 Pages) Microchip Technology – PIC32 Flash Programming Specification

5.2 4-wire JTAG Details
The 4-wire interface uses standard JTAG (IEEE
1149.1-2001) interface signals.
• TCK: Test Clock – drives data in/out
• TMS: Test Mode Select – selects operational mode
• TDI: Test Data In – data into the device
• TDO: Test Data Out – data out of the device
FIGURE 5-3:
TCK
TMS
‘1’
TDI
TDO
4-WIRE JTAG INTERFACE
‘1’
‘0’
‘0’
iLSb
oLSb
PIC32
Since only one data line is available, the protocol is
necessarily serial (like SPI). The clock input is at the
TCK pin. Configuration is performed by manipulating a
state machine bit by bit through the TMS pin. One bit of
data is transferred in and out per TCK clock pulse at the
TDI and TDO pins, respectively. Different instruction
modes can be loaded to read the chip ID or manipulate
chip functions.
Data presented to TDI must be valid for a chip-specific
setup time before, and hold time, after the rising edge
of TCK. TDO data is valid for a chip-specific time after
the falling edge of TCK (refer to Figure 5-3).
‘1’
iMSb
oMSb
‘1’
‘0’
 2007-2013 Microchip Technology Inc.
DS61145L-page 13