Preliminary Technical Information

AD6426

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Revision Preliminary 2.3 (June 9, ´98)

- 29 -

Confidential Information

DoBist Instruction

This instruction is provided to support engineering mode test.

When the instruction is loaded, it will generate an NMI to the

H8 processor. This will enable special software to be executed

which can be used to test the operation of the device. During

this time, the 8-bit DoBist register is selected for scan,

enabling a result code for the test to be scanned out. For the

duration of the test, all I/O retain their normal function. The

test program must therefore cope with undefined inputs, but is

able to communicate with other devices to extend the test

procedure. This allows the NMI to be generated during normal

phone operation. This instruction is only valid during the

normal operation of the AD6426; i.e. in Mode A.

Mode D Instruction

This instruction switches the AD6426 into the H8 Emulation

Mode (Mode D). It is only valid to switch modes while the

AD6426 is held in reset.

Reset

To comply with the IEEE specification, the JTAG interface

will be forced to reset whenever the JTAG Port is re-enabled.

This will select the Bypass register and force the AD6426 into

the Normal Mode (Mode A).

Debug Port Interface

In normal (voice-service) operation, the Universal Serial Port

can be used as a monitor port, which allows monitoring

internal operation of the channel codec section. However,

during the use of GSM Data Services, the USC is engaged in

data communication and cannot be used for monitoring. The

6426 provides a Debug Port to enable monitoring and

debugging in this case. This is in the form of a simple 2 pin

UART. The communication format is fixed at 9600 baud, 8

data bits, one stop bit, no parity, asynchronous

communication. Operation of the Debug Port is under control

of the Layer 1 software.

Two of the GPIO pins can be programmed to be used as the

Debug Port:

Pin Name

New Function

GPIO8

TXDATA

GPIO9

RXDATA

The serial port can be enabled by asserting the flag DATA

SERIAL PORT SELECT in CC Control Register 7.

MODES OF OPERATION

The AD6426 can be switched between two main operating

modes, using instructions downloaded via the JTAG interface.

This must be done while the AD6426 is held in reset. Once

the instruction load is completed the pins are immediately set

to reflect the new operating mode. Table 23 shows these

modes. The modes B and C are reserved and are not available

to the user.

Table 23. Modes of Operation

Mode of Operation

A

Normal Mode

B

Reserved

C

Reserved

D

Emulation Mode (H8)

Normal Mode (Mode A)

This mode is used during normal operation of the AD6426. All

JTAG-pins have their normal functionality, when enabled by

JTAGEN and can be used for production test.

Emulation Mode (Mode D)

Selecting Mode D allows the emulation of the internal H8

processor. In this Mode several pins assume a new

functionality or are no longer available. Table 24 lists all pins,

which have different functionality or direction in the

Emulation Mode compared to the Normal Mode.

In Emulation Mode the internal DSP remains active but will

not have access to external memory devices. The internal H8

will be switched into hardware stand-by mode; the LCD

controller interface and Boot Code ROM remain functional.

CCIRQ0 : 2 are channel codec interrupts to the emulator.

CCIRQ2 is defined in CC Control Registers 77 and 78.

Table 24. Pin Functions in Mode D

Pin Name in

Normal Mode (A)

Pin Function in

Emulation Mode (D)

IRQ6

CCCS

I

ADD19 : 16

-

TRI

ADD15 : 0

ADD15 : 0

I

DATA7 : 0

-

TRI

RD

RD

I

HWR

HWR

I

LWR

-

TRI

RAMCS

-

TRI

SIMCARD

-

TRI

SIMDATAOP

-

TRI - O

SIMDATAIP

-

I

SIMCLK

-

O

SIMRESET

CCIRQ0

O

SIMPROG

CCIRQ2

O

SIMSUPPLY

CCIRQ1

O

GPIO9

H8CS0

I

GPIO8

CCGPIO8

I/O -

TRI