NEC PD750004, PD750006, PD750008, PD75P0016 - page 122

102

µPD750008 USER'S MANUAL

5.3.5 Operation of the Watchdog Timer

When WDTM is set to 1, the basic interval timer/watchdog timer functions as a watchdog timer. An internal

reset signal is generated when the basic interval timer (BT) overflows. No reset signal, however, is generated

during the oscillation wait time following the STOP instruction has been released (WDTM cannot be cleared

without using reset). BT is constantly incremented by the clock supplied from the clock generator. It cannot

be stopped from counting.

In the watchdog timer mode, program crashes are detected using the intervals at which BT overflows. The

interval can be selected from among four values depending on bits 2 to 0 of BTM (see Figure 5-24). Select

an interval for detecting crashes according to the user system. A large program should be divided into modules

each of which can be executed within the set interval. Include an instruction which clears BT at the end of

each module. If execution does not reach the instruction which clears BT within the set interval (in which case

a program error leading to a program crash may have occurred), BT overflows and an internal reset signal

is generated to forcibly terminate the program. The occurrence of internal reset possibly means that a program

crash has occurred. A crash can thus be detected.

Set the watchdog timer as follows (<1> and <2> can be performed with the same instruction):

<1> Set the interval in BTM.

<2> Set 1 in bit 3 of BTM. Initial settings

<3> Set 1 in WDTM.

<4> After <1> to <3> are set, set 1 in bit 3 of BTM within each interval.

Example Use the basic interval/watchdog timer as a watchdog timer with 5.46-ms interval (at 6.00 MHz)

A program is divided into several modules each of which can be executed within the interval

set in BTM (5.46 ms). BT is cleared at the end of each module. If a program crash occurs, BT

overflows and an internal reset signal is generated because BT is not cleared within the set

interval.

(From now on, 1 is set in bit 3 of BTM at intervals of 5.46 ms.)

SET1

SEL

MOV

MOV



SET1

MBE

MB15

A, #1101B

BTM, A



WDTM







; Specifies a time interval and 

; starts processing.

; Enables the watchdog timer.

···

Initial setting:

*

Contents

Main PD750008 USER'S MANUAL Page Page Major Changes The mark * shows major revised points. Page Page Page Page CONTENTS Page Page Page Page LIST OF FIGURES (1/4) LIST OF FIGURES (2/4) LIST OF FIGURES (3/4) LIST OF FIGURES (4/4) LIST OF TABLES (1/2) Page Page CHAPTER 1 GENERAL 2 1.1 FUNCTION OVERVIEW Page Page 5 CHAPTER 1 GENERAL 1.4 BLOCK DIAGRAM ( ) 6 Note Connect IC (VPP) to VDD, keeping the wiring as short as possible. Remark ( ) : PD75P0016. 7 Note Connect IC (VPP) to VDD, keeping the wiring as short as possible. Remark ( ) : PD75P0016. Page CHAPTER 2 PIN FUNCTIONS Page 11 CHAPTER 2 PIN FUNCTIONS Table 2-2. Non-Port Pin Functions Page Page Page Page Page Page Page 19 CHAPTER 2 PIN FUNCTIONS P-ch Note IN/OUT 20 2.4 CONNECTION OF UNUSED PINS Table 2-3. Connection of Unused Pins Note ( ): PD75P0016 CHAPTER 3 FEATURES OF THE ARCHITECTURE AND MEMORY MAP Page Page 24 Figure 3-2. Data Memory Organization and Addressing Range of Each Addressing Mode Remark : Don't care 25 Table 3-1. Addressing Modes Page Page Page Page Page Page Page Page Page Page Page 37 Figure 3-5. General Register Configuration (4-bit Processing) 38 Figure 3-6. General Register Configuration (8-bit Processing) Page 40 Figure 3-7. PD750008 I/O Map (1/5) 41 Figure 3-7. PD750008 I/O Map (2/5) 42 Figure 3-7. PD750008 I/O Map (3/5) 43 Figure 3-7. PD750008 I/O Map (4/5) Note Whether a bit can be read or written depends on the bit. 44 Figure 3-7. PD750008 I/O Map (5/5) CHAPTER 4 INTERNAL CPU FUNCTIONS Page Page Page 49 Figure 4-3. Program Memory Map (in PD750004) 50 Figure 4-4. Program Memory Map (in PD750006) 51 Figure 4-5. Program Memory Map (in PD750008) 52 Figure 4-6. Program Memory Map (in PD75P0016) Page Page Page Page Page Page 59 Figure 4-11. Format of Stack Pointer and Stack Bank Select Register Note PC12 and PC13 are 0 in the PD750004. PC13 is 0 in the PD750006 and PD750008. 60 Figure 4-13. Data Restored from the Stack Memory (Mk I Mode) 61 Figure 4-15. Data Restored from the Stack Memory (Mk II Mode) Page Page Page Page Page CHAPTER 5 PERIPHERAL HARDWARE FUNCTIONS Page 69 Figure 5-2. Configurations of Ports 0 and 1 70 Figure 5-3. Configurations of Ports 2 and 7 Note For port 7 only 71 Figure 5-4. Configurations of Ports 3n and 6n (n = 0 to 3) Internal bus Note For port 6n only 72 Figure 5-5. Configurations of Ports 4 and 5 73 Figure 5-6. Configuration of Port 8 Page 75 Figure 5-7. Formats of Port Mode Registers Port mode register group A Port mode register group B Port mode register group C Page Page 78 Table 5-2. I/O Pin Manipulation Instructions Page 80 Table 5-3. Operations by I/O Port Manipulation Instructions <1> : Represents an addressing mode PORTn.bit or PORTn.@L. Page Page Page 84 Page Page 87 Figure 5-12. Format of the Processor Clock Control Register Remarks 1. f : Output frequency from the main system clock oscillator 2. f : Output frequency from the subsystem clock oscillator Page Page Page Page Page Page Page Page Page 97 Note Caution Be sure to write a 0 in bit 2 of the CLOM. is the CPU clock selected by PCC. Page Page 100 Page Page Page Page Page 106 107 Remark ( ) for fW = 32.768 kHz Page 109 TOUT0 Figure 5-28. Block Diagram of the Timer/Event Counter (Channel 0) 110 Figure 5-29. Block Diagram of the Timer Counter (Channel 1) Page 112 Figure 5-30. Timer/Event Counter Mode Register (Channel 0) Format = 4.19 MHz Count pulse (CP) selection bit = 6.00 MHz 113 Figure 5-31. Timer Counter Mode Register (Channel 1) Format = 4.19 MHz Count pulse (CP) select bit = 6.00 MHz Page 115 Count pulse (CP) selection bit 116 Page Page Page Page Page Page Page Page 125 Figure 5-39. Block Diagram of the Serial Interface Page Page Page 129 Remark x: Dont care Serial clock selection bit (W) Remarks 1. Each mode can be selected using CSIE, CSIM3, and CSIM2. Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page 161 Figure 5-60. Operations of RELT, CMDT, RELD, and CMDD (Master) Figure 5-61. Operations of RELT, CMDT, RELD, and CMDD (Slave) Page Page Page 165 Table 5-10. Various Signals Used in the SBI Mode (1/2) 166 Table 5-10. Various Signals Used in the SBI Mode (2/2) Notes 1. When WUP = 0, IRQCSI is always set on the ninth rising edge of the SCK signal. Page Page 169 Figure 5-67. Address Transfer Operation from Master Device to Slave Device (WUP = 1) 170 Figure 5-68. Command Transfer Operation from Master Device to Slave Device 171 Figure 5-69. Data Transfer Operation from Master Device to Slave Device 172 Figure 5-70. Data Transfer Operation from Slave Device to Master Device Page Page Page Page Page Page Page Page Page Page CHAPTER 6 INTERRUPT AND TEST FUNCTIONS 184 Figure 6-1. Block Diagram of Interrupt Control Circuit* Note Noise eliminator (when the noise eliminator is selected, standby mode cannot be released.) 185 < < Page Page 189 Figure 6-3. Interrupt Priority Specification Register Page 191 INT4 (c) Configuration of the INT4 circuit (b) Configuration of the INT1 circuit INT4/P00 192 Figure 6-5. I/O Timing of a Noise Eliminator Remark tSMP = tCY or 64/fX 193 Figure 6-6. Format of Edge Detection Mode Registers (a) INT0 edge detection mode register (IM0) (b) INT1 edge detection mode register (IM1) Page 195 Page Page Page Page Page Page Page 203 (1) Interrupt enable/disable Interrupt disabled INT0 and INTT0 enabled INTT0 enabled Interrupt disabled <Main program> <1> Reset <2> EI IE0 EI IET0 <3> EI <4> DI IE0 <5> DI 204 ; RBE = 0 <INT0 service program> <5> RETI Status 1 Page 206 (4) Execution of held interrupts (interrupt requests when interrupts are disabled) RETI <2> EI RETI 207 (5) Execution of held interrupts two interrupts with lower priority occur concurrently <INTT0 service routine> RETI <1> Page 209 <1> INTCSI <5> <3> INTT0 Status 1 Page Page 212 Figure 6-10. Block Diagram of the INT2 and KR0 to KR7 Circuits Page Page CHAPTER 7 STANDBY FUNCTION Page Page Page Page Page = .. Page Page Page CHAPTER 8 RESET FUNCTION 226 Table 8-1. Status of the Hardware after a Reset (1/2) 227 CHAPTER 8 RESET FUNCTION Table 8-1. Statuses of the Hardware after a Reset (2/2) Page CHAPTER 9 WRITING TO AND VERIFYING PROGRAM MEMORY (PROM) Page 231 Page Page Page CHAPTER 10 MASK OPTION Page CHAPTER 11 INSTRUCTION SET Page Page Page Page Page 243 (3) Explanation of symbols used for the addressing area column Page Page 246 Page Page 249 Note The shaded portion is supported in Mk II mode only. 250 251 Page Page Page 255 256 257 258 Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page APPENDIX A FUNCTIONS OF THE PD75008, PD750008, AND PD75P0016 A Page 301 APPENDIX B DEVELOPMENT TOOLS * 302 PROM programming tools 303 APPENDIX B DEVELOPMENT TOOLS Page 305 APPENDIX B DEVELOPMENT TOOLS + Development Tool Configuration Page Page Page APPENDIX C MASKED ROM ORDERING PROCEDURE C Page APPENDIX D INSTRUCTION INDEX D Page Page Page Page Page APPENDIX E HARDWARE INDEX E Page Page Page 321 APPENDIX F REVISION HISTORY Major revisions in this edition are shown below. The revised chapters refer to this edition. F