epda2.pdf

Inserting and Removing the PDA From the PlayStation

If a PocketStation (PDA) application is written so that it can operate when the PDA is inserted in the

PlayStation (PS), the functions described below must be implemented so that the PDA can

communicate (be recognized) as a Memory Card. This is unnecessary, however, if the application

is written so that it exits and returns to the clock screen or another screen while the PDA is

plugged into the PS.

Communication with the PS is performed by the PDA kernel. When the PDA is inserted or

removed, the PDA application must explicitly switch communication with the PS on and off. The

following is a description of kernel operations that take place when the PDA is inserted or removed

from the PS as well as the operations that the PDA application should perform.

Kernel operations performed when the PDA is inserted or removed from the PS

When the PDA is inserted or removed from the PS, a BATIRQ is generated. The kernel performs

the following operations during BATIRQ interrupt handling. BATIRQ must be enabled beforehand.

Insertion

Invert LCD. Turn off DAC, speaker, IR, LED.

Set bit8 of PDA status to 1.

Removal

Normal LCD display.

Set bit8 of PDA status to 1.

Kernel operations during communication with the PS

A SPIFIQ is generated during communication with the PS. Communication is performed by the

kernel in the SPIFIQ interrupt handling routine. Since communication takes up significant processor

resources, PDA application speed can be affected as a result. Also, if TC2FIQ interrupt handling is

resource intensive, normal communication with the PS may not be possible. Therefore, it is safer to

disable TC2FIQ when the PDA is inserted into the PS.

System calls

In order to enable communication with the PS, a system call must be used and operation must

switch to kernel mode. The following describes the operations performed by the system calls used

for communication with the PS.

[ SWI 5 ]

Checks the PDA status and updates PDA status contents if the insertion/removal flag is set. Then

performs the same operations as [ SWI 17 Argument 1]. Does nothing if no insertion/removal has

occurred.

[ SWI 6 ]

Returns address held in PDA status. If there has been an insertion/removal, bit8 of the PDA status

is set to 1. If communication with the PS is enabled, bit9 is set to 1.

[ SWI 17 Argument 1 ]

If the PDA is inserted in the PS, turns on communication with the PS and sets the clock frequency

to 4 MHz.

If the PDA is not inserted in the PS, turns off communication with the PS.

[ SWI 17 Argument 0 ]

Turns off communication with the PS.

Operations that should be performed by the PDA application.

The following are examples of operations that should be performed by the PDA application.

1. Monitor the PDA status in the main loop to determine if insertion/removal has taken place.

2. If insertion/removal has taken place, determine if it was insertion or removal.

3. If insertion, turn on communication with the PS. (Clock frequency set to 4 MHz).

Disable TC2FIQ.

4. If removal, restore clock.

If necessary, turn devices such as DAC back on.

Other issues

If the PDA application is started in response to a PS request from libmcx, the "connected to PS"

status cannot be determined from the PDA status at startup. This must be determined by checking

the register directly.

(This is not required for applications that do not need to be started up from the PS.)

Also, upon exit the application must always turn off communication with the PS through [ SWI 17

Argument 0 ].

Sample program

AREA

MAIN_BSS, DATA, READWRITE

; RAM AREA

status_addr

; PDA status address

CODE32

AREA

MAIN, CODE, READONLY

main

; startup operations

connect_check

; check for connection with PS

SWI

; get PDA status address beforehand

LDR

r5, =status_addr ;

STR

r4, [r5]

main_loop

; main routine operations

LDR

r5, =status_addr

LDR

r4, [r5]

; r4 status address

LDR

r5, [r4]

; r5 status contents

TST

r5, #0x100

BLNE

switch_mode

; change mode if there was insertion/removal

switch_mode

STMDB sp!, {r4-r5, lr}

SWI

; If insertion, enable PS communication (4 MHz)

; If removal, disable PS communication

LDR

r5, =status_addr ; recheck status

LDR

r4, [r5]

; r4 status address

LDR

r5, [r4]

; r5 status contents

TST

r5, #0x200

; PS communication not enabled, i.e. "removed"

MOVEQ r4, #5

SWIEQ 4 ; restore clock to 1MHz

; PS communication enabled, i.e. "inserted"

MOVNE r4, #0x0a000000 ; INTStatus

MOVNE r5, #0x2000

STRNE r5, [r4, #0x0c]

; disable TC2FIQ

LDMIA sp!, {r4-r5, pc}

connect_check

STMDB sp!, {r4-r5, lr}

MOV

r5, #0x0d800000 ; PIOControl

LDR

r4, [r5, #0x0c]

; check PIOReadInputData

TST r4, #0x10

; when connected to PS

MOVNE r5, #0x0d000000 ; LCDControl

LDRNE r4, [r5]

ORRNE r4, r4, #0x80

STRNE r4, [r5]

; invert LCD

MOVNE r4, #1

SWINE 17

; enable communication with PS (4MHz)

LDMIA sp!, {r4-r5, pc}

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