OLIMEX© 2015
IMX233-OLinuXino-MAXI user's manual
The HW_DIGCTL_CTRL_USE_SERIAL_JTAG bit in the digital control block selects whether the
one-wire serial JTAG interface or the alternative six-wire parallel JTAG interface is used. There are
other options in the digital control block which might interest you and our advice is to check the
iMX233's datasheet released by Freescale.
SJTAG
Pin # Signal Name
Processor Pin #
1
3.3VREG
-
2
GND
30, 35, 98, 105, 112, 118
3
SJTAG_PSW
119
4
DEBUG
84
The pin names are also written at the bottom of the board for your convenience.
6.1.3 Classic JTAG debug
The third option is to use the classic 6-pin parallel JTAG (not including GND and VCC). There are
pads left for this option at the bottom of the board under the SD card holder. They are named
individually and framed near a “JTAG” name.
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 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 = 0×1 Use
one-wire serial JTAG mode.
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