5 Configuration Mode Introduction
5.2 JTAG Configuration
UG290-2.3E
20(87)
mode.
5.2.1
JTAG Configuration Mode Pins
The relevant pins for the JTAG configuration mode are shown in Table
Table 5-3 Pin Description in JTAG Configuration Mode
Pin Name
I/O
Description
JTAGSEL_N
1
I, internal weak
pull-up
Revert JTAG pin from GPIO to configuration
pin. Low active
TCK 2
I
JTAG serial clock input
TMS
2
I, internal weak
pull-up
JTAG serial mode input
TDI
I, internal weak
pull-up
JTAG serial data input
TDO
O
JTAG serial data output
Note!
[1] The JTAGSEL_N works only when the JTAG pin is set as a GPIO and the device
starts to work. For the LittleBee
®
Family of FPGA products, when MODE[2
:
0]= 001,
the JTAGSEL_N pin and the four JTAG pins (TCK, TMS, TDI, TDO) can be set as
GPIOs simultaneously, but the JTAG pin cannot be recovered as a configuration pin
by JTAGSEL_N. It can be recovered when the device reenters the editing mode.
[2] TCK needs to connect 4.7 K pull down resister on the PCB.