MSX Family Data Sheet
22
[Rev. 1.10] 9/5/01
I-Cube, Inc.
1.5.4
JTAG Input Format
1.5.5
JTAG Instructions
Table 8
JTAG Input Format
Instruction
Control
Address
Bit Number
15
14
13
12
11
10
9876
5432
1
0
Bit Name
I3
I2
I1
I0
C1
C0
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
Table 9
JTAG Instructions
I3 I2 I1 I0
Instruction
Description
1
1 1 Bypass
Places device in a mode to pass TDI data to TDO with one clock delay. Used
for programming and testing devices through serial connected JTAG controls.
1
1 0 Control Register
Shifts data in and out of the Control Register. Capture, shift, and write the
Control Register.
1
0 1 IO Buffer and Crosspoint Array
Reset, Device ID out
Resets IOBs for the Ports to Input and clear all Ports to Disconnect. The
device ID is serialized out to TDO. The Instruction serialized out is the
RESET Instruction during the Instruction phase. Update is forced to the
crosspoint array.
1
0 0 Device ID out
Serialize the device ID and revision history out to TDO. ID for the MSX is
0x0000A89F.
1
0
1 1 Set the JTAG Address Register
Set the 10-bit JTAG Address Register with the lower ten bits of the JTAG
Instruction Register. The lower ten bits of the JTAG Address Register become
the ’B’ Address for Crosspoint Access.
1
0
1 0 Access the Crosspoint Array and
Update Array
Read or Write the crosspoint addressed by the lower ten bits of the JTAG
Instruction (A Address) and the JTAG Address Register or Address Counter
(B Address). Read data is shifted out on TDO.
C1 C0=0 0 Read Switch with A and B Address. Increment ’B’ address with
each ShiftDR.
C1 C0=0 1 Connect switch at location Addressed with A and B. Increment
’B’ address with each ShiftDR. Activate with UpdateDR.
C1 C0=1 0 Disconnect switch at location Addressed with A and B.
Increment ’B’ address with each ShiftDR. Activate with UpdateDR.
C1 C0=1 1 Force update of Switch Array Shadow register. Activate with
UpdateDR.
1
0
0 1 Disconnect a Port in the
Crosspoint Array
Disconnect all Ports from the Port Addressed by the lower ten bits of the
JTAG Instruction. The addressed port is reset to disconnect. The programmed
state of the IOB is not changed.
1
0
0 0 Clear the Crosspoint Array
Clear the crosspoint array at no-connect. Leave the IOBs unchanged.
0
1
1 1 Shift the IO Buffer Data Register Shift twenty bits of data into and out of the IOB Data register. The data is
used to program the IOBs. Parallel shift twenty bits into IOB Copy Register.
0
1
1 0 Shift out the IOB Copy Register Shifts twenty bits of data out of the IOB Copy Register. Data is either the IOB
Data register shifted in by instruction 0111 or the last JTAG IOB Read Data.