GMS30C7201 Datasheet, PDF (315/352 Pages) Hynix Semiconductor – 60MHz operation frequency Low power consumption

Debug and Test Interface
14.3.1 Reset
Note
The boundary-scan interface includes a state-machine controller (the TAP controller). A
pulldown resistor is included in the nTRST pad which holds the TAP controller state machine
in a safe state after power up. In order to use the boundary scan interface, nTRST should be
driven HIGH to take the TAP state machine out of reset.
The action of reset (either a pulse or a DC level) is as follows:
• System mode is selected (i.e. the boundary scan chain does NOT intercept any of the
signals passing between the pads and the core).
• IDcode mode is selected. If TCK is pulsed, the contents of the ID register will be
clocked out of TDO.
The TAP controller inside GMS30C7201 contains a scan chip register which is reset to the
value b0011 thus selecting the boundary scan chain. If this register is programmed to any value
other than b0011, then it must be reprogrammed with b0011 or a reset applied before boundary
scan operation can be attempted.
14.3.2 Pullup Resistors
The IEEE 1149.1 standard requires pullup resistors in the input pins. However, to ensure safe
operation an internal pulldown is present in the nTRST pin and therefore will have to be driven
HIGH when using this interface.
Pin
Internal
Resistor
TCLK
Pullup
nTRST
Pulldown
TMS
Pullup
TDI
Pullup
Table 14-1: Internal Resistors for Input Pins
14.3.3 Instruction Register
The instruction register is 4 bits in length.
There is no parity bit. The fixed value loaded into the instruction register during the CAPTURE-
IR controller state is: 0001.
14.3.4 Public Instructions
The following public instructions are supported:
GMS30C7201 Data Sheet
Instruction
Binary Code
EXTEST
0000
SAMPLE/PRELOAD 0011
CLAMP
0101
HIGHZ
0111
Table 14-2: Supported Public Instructions
14-5