4501 datasheet(198/212 Pages) RENESAS

198 / 212 page

3.3 List of precautions

3-29

4501 Group

APPENDIX

Rev.2.01

Feb 07, 2005

REJ09B0192-0201

(6)

Power down instruction

Be sure to disable interrupts by executing the DI instruction before executing the EPOF instruction.

Note [2] on bit 3 of register I1

When the bit 3 of register I1 is cleared to “0”, the RAM back-up mode is selected and the input of

INT pin is disabled, be careful about the following notes.

• When the key-on wakeup function of port P13 is not used (register K13 = “0”), clear bits 2 and 3

of register I1 before system enters to the RAM back-up mode. (refer to Figure 3.3.2 ➀).

0 ; (00✕✕2)

TI1A

; Input of INT disabled .................... ➀

EPOF

POF

; RAM back-up

✕ : these bits are not used here.

Fig. 3.3.2 External 0 interrupt program example-2

Note [3] on bit 2 of register I1

When the interrupt valid waveform of the P13/INT pin is changed with the bit 2 of register I1 in

software, be careful about the following notes.

• Depending on the input state of the P13/INT pin, the external 0 interrupt request flag (EXF0) may

be set when the bit 2 of register I1 is changed. In order to avoid the occurrence of an unexpected

interrupt, clear the bit 0 of register V1 to “0” (refer to Figure 3.3.3 ➀) and then, change the bit 2

of register I1.

In addition, execute the SNZ0 instruction to clear the EXF0 flag to “0” after executing at least one

instruction (refer to Figure 3.3.3 ➁).

Also, set the NOP instruction for the case when a skip is performed with the SNZ0 instruction (refer

to Figure 3.3.3 ➂).

; (✕✕✕02)

TV1A

; The SNZ0 instruction is valid ..... ➀

12 ; (✕1✕✕2)

TI1A

; Interrupt valid waveform is changed

NOP

........................................................... ➁

SNZ0

; The SNZ0 instruction is executed

(EXF0 flag cleared)

NOP

........................................................... ➂

✕ : these bits are not used here.

Fig. 3.3.3 External 0 interrupt program example-3

4501 Datasheet(PDF) 198 Page - Renesas Technology Corp

4501 Datasheet(HTML) 198 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL