Segger J-Link User Manual page 168

168
Variable
JTAG_IRLen
JTAG_TotalIRLen
JTAG_AllowTAPReset
JTAG_Speed
JTAG_ResetPin
JTAG_TRSTPin
JTAG_TCKPin
JTAG_TDIPin
JTAG_TMSPin
EMU_ETB_IsPresent
Table 5.10: Global DLL variables
J-Link / J-Trace (UM08001)
CHAPTER 5
Description
IR-Len (in bits) of the device we want to commu-
nicate with.
Example
JTAG_IRLen = 4;
Computed automatically, based on the values of
JTAG_IRPre, JTAG_DRPre,
JTAG_DRPost.
Example
v = JTAG_TotalIRLen;
En-/Disables auto-JTAG-detection of J-Link. Has
to be disabled for devices which need some spe-
cial init (for example to add the core to the JTAG
chain), which is lost at a TAP reset.
Allowed values
0 Auto-detection is enabled.
1 Auto-detection is disabled.
Sets the JTAG interface speed. Speed is given in
kHz.
Example
JTAG_Speed = 2000; // 2MHz JTAG speed
Pulls reset pin low / Releases nRST pin. Used to
issue a reset of the CPU. Value assigned to reset
pin reflects the state. 0 = Low, 1 = high.
Example
JTAG_ResetPin = 0;
SYS_Sleep(5); // Give pin some time to get low
JTAG_ResetPin = 1;
Pulls reset pin low / Releases nTRST pin. Used to
issue a reset of the debug logic of the CPU. Value
assigned to reset pin reflects the state. 0 = Low,
1 = high.
Example
JTAG_TRSTPin = 0;
SYS_Sleep(5); // Give pin some time to get low
JTAG_TRSTPin = 1;
Pulls TCK pin LOW / HIGH. Value assigned to
reset pin reflects the state. 0 = LOW, 1 = HIGH.
Example
JTAG_TCKPin = 0;
Pulls TDI pin LOW / HIGH. Value assigned to
reset pin reflects the state. 0 = LOW, 1 = HIGH.
Example
JTAG_TDIPin = 0;
Pulls TMS pin LOW / HIGH. Value assigned to
reset pin reflects the state. 0 = LOW, 1 = HIGH.
Example
JTAG_TMSPin = 0;
If the connected device has an ETB and you want
to use it with J-link, this variable should be set to
1. Setting this variable in another function as
InitEmu() does not have any effect.
Example
void InitEmu(void) {
EMU_ETB_IsPresent = 1;
}
© 2004-2013 SEGGER Microcontroller GmbH & Co. KG
Working with J-Link and J-Trace
and
JTAG_IRPost
R/W
R
R
W
W
W
W
R/W
R/W
R/W
W