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11.3. Functional test

In AMBA functional test mode, the SSM disconnects the functional ARM920T from its inputs and disables its output drivers. The SSM provides locations that can be accessed by the tester. There are 9 locations that can be accessed in functional test mode:

  • 3 write locations

  • 6 read locations.

These are bit-mapped to AIN[10:2] as shown in Table 11.2.

Note

TAPID[31:0] and ETM<name>, the ARM920T Trace Interface Port, are not accessible in this test mode

AMBA functional test locations

AIN bit

Location

Read/write

Data

10

CPDIN

Write

31:0

9

A920Inputs

Write

31:0

8

DIN

Write

31:0

7

DOUT

Read

31:0

6

CPDOUT

Read

31:0

5

CPID

Read

31:0

4

A920Status1

Read

21:0

3

A920Status2

Read

31:0

2

AOUT

Read

31:0

The A920Inputs location, shown in Table 11.12, is constructed as shown in Table 11.3.

Construction of A920Inputs location

A920 inputs bit

Signal

31

AGNT

30

WAITIN

29

ERRORIN

28

LASTIN

27

BnRES

26

FCLK

25:20

0

19

VINITHI

18

nFIQ

17

nIRQ

16

ISYNC

15:14

CHSDE[1:0]

13:12

CHSEX[1:0]

11

TRACK

10

IEBKPT

9

DEWPT

8

EDBGRQ

7

EXTERN0

6

EXTERN1

5

TCK

4

TDI

3

TMS

2

nTRST

1

SDOUTBS

0

DBGEN

The A920Status1 location, shown in Table 11.2, is constructed as shown in Table 11.4.

Construction of A920Status1 location

A920Status1 bits

Signal

21

WRITEOUT

20:19

SIZE

18:17

PROT[1:0]

16:15

BURST[1:0]

14

AREQ

13

LOK

12

TRAN

11

ENBA

10

ENBD

9

FCLKOUT

8

CPCLK

7

nCPWAIT

6

nCPMREQ

5

CPPASS

4

CPLATECANCEL

3

CPTBIT

2

nCPTRANS

1

BIGENDOUT

0

INSTREXEC

The A920Status2 location, shown in Table 11.2, is constructed as shown in Table 11.5.

Construction of A920Status2 location

A920Status2 bits

Signal

31

DRIVEOUTBS

30

DBGACK

29

ECLK

28:25

IR[3:0]

24

RANGEOUT0

23

RANGEOUT1

22:18

SCREG[4:0]

17:14

TAPSM[3:0]

13

TDO

12

NTDOEN

11

SDIN

10

SHCLK1BS

9

SHCLK2BS

8

ICAPCLKBS

7

ECAPCLKBS

6

PCLKBS

5

TCK1

4

TCK2

3

RSTCLKBS

2

COMMRX

1

COMMTX

0

DBGRQI

You can update and examine the inputs and outputs of the ARM920T on a per-cycle basis by writing to the input locations and reading from the output locations. The functional ARM920T is clocked after every sequence of writes. This means that for every cycle, at least one location must be written to (usually A920Inputs), but no locations have to be read. A typical AMBA test iterates the sequence:

  • address locations to be written and read

  • write input locations

  • read output locations

  • turnaround vector.

When the locations have been addressed, they are sequenced through in the order shown in Figure 11.1.

Figure 11.1. AMBA functional test state machine

Figure 11.1. AMBA functional test state machine
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