MEC1322 Datasheet, PDF (383/456 Pages) Microchip Technology – Keyboard and Embedded Controller for Notebook PC

MEC1322
36.2.3 TEST PROCEDURE
36.2.3.1 Setup
Warning: Ensure power supply is off during Setup.
1. Connect JTAG_RST# to ground.
2. Connect the VSS, AVSS, VSS_VBAT pins to ground.
3. Connect the VCC1, AVCC, VBAT pins to an unpowered 3.3V power source.
4. Connect the VREF_PECI pin to an unpowered 1.8V power source.
5. Connect an oscilloscope or voltmeter to the Test Output pin.
6. All other pins should be tied to ground.
Note: There are 101 pins in the XNOR Chain.
36.2.3.2 Testing
1. Turn on the 3.3V power source.
2. Enable the XNOR Chain as defined in Section 36.2.3.3, "Procedure to Enable the XNOR Chain".
Note:
At this point all inputs to the XNOR Chain are low, except for the JTAG_RST# pin, and the output on the
Test Output pin is non-inverted from its initial state, which is dependent on the number of pins in the chain.
If the number of input pins in the chain is an even number, the initial state of the Test Output Pin, pin 17:
KSO04/GPIO103/TFDP_DATA/XNOR is low. If the number of input pins in the chain is an odd number, the
initial state of the Test Output Pin, pin 17: KSO04/GPIO103/TFDP_DATA/XNOR is high.
3. Bring one pin in the chain high. The output on the Test Output Pin, pin 17: KSO04/GPIO103/TFDP_-
DATA/XNOR pin should toggle. Then individually toggle each of the remaining pins in the chain. Each time an
input pin is toggled either high or low the Test Output Pin, pin 17: KSO04/GPIO103/TFDP_DATA/XNOR pin
should toggle.
4. Once the XNOR test is completed, exit the XNOR Chain Test Mode by cycling VCC1 power.
36.2.3.3 Procedure to Enable the XNOR Chain
//BEGIN PROCEDURE TO ENTER XNOR CHAIN
///////////////////////////////////
//Reset Test Interface
///////////////////////////////////
force JTAG_RST# = 0
force KSO00/GPIO000/JTAG_TCK = 0
force KSO02/GPIO101/JTAG_TDI = 0
force KSO01/GPIO100/JTAG_TMS = 1
Wait 100 ns
////////////////////////////////
//Come out of reset
////////////////////////////////
force TRST#/JTAG_RST# = 1
Wait 100 ns
force KSO00/GPIO000/JTAG_TCK = 1
force KSO00/GPIO000/JTAG_TCK = 0
force KSO00/GPIO000/JTAG_TCK = 1
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DS00001719D-page 383