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You can also check the pin names at the top and at the bottom of the board around the U_DEBUG
pins.
6.1.2 JTAG debug
This option allows you to use the classic 6-pin parallel JTAG (not including GND and VCC). There
are pads left for this option at the top of the board over the SD card holder.
The important thing is that these pins are multiplexed with the SD card signals. In order to use the
6-pin JTAG you will have to stop using the SD card. Note also that the classic JTAG interface
comes without plastic header mounted so in order to use it you will need to use wires for
connection.
Consider the software settings required to switch from SJTAG to 6-pin JTAG and vice verse
referring to the iMX233 manual. For instance:
The HW_DIGCTL_CTRL_USE_SERIAL_JTAG bit in the digital control block selects whether the
serial JTAG interface or the alternative six-wire parallel JTAG interface is used.
HW_DIGCTL_CTRL_USE_SERIAL_JTAG – 0×0 – selects whether the one-wire serial JTAG
interface or the alternative six-wire parallel JTAG interface is used. 0 = Parallel six-wire JTAG is
enabled and is mapped to a collection of module pins that must be enabled by programming their
MUXSEL bits in the pin control block. 1 = Serial JTAG is enabled and uses the dedicated DEBUG
pin. The ROM bootcode writes this field prior to enabling JTAG, selecting which type of JTAG pin
signaling to use. OLD_JTAG = 0×0 Use six-wire parallel JTAG mode. SERIAL_JTAG = 0x1 Use
one-wire serial JTAG mode.
It is good idea to check the datasheet of the iMX233 processor for all the options in the digital
control block. The processor's datasheet should be always the first piece of paper you consult when
dealing with electronics.
JTAG (multiplexed with SD card)
Pin #
Signal name
1
SSP1_DATA1
2
SSP1_DATA0
3
GND
4
SSP1_SCK
5
SD_VCC
6
SSP1_CMD
7
SSP1_DATA3
8
SSP1_DATA2
Processor pin#
85
84
-
90
-
83
87
86
Page 19 of 36
iMX233-OLinuXino-NANO user's manual
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