NEC PD75402A, PD75P402 - page 144

133

CHAPTER 6. INTERRUPT FUNCTIONS

(4) Interrupt status flag

The interrupt status flag (IST0) is the flag which shows the status of the processing currently being executed by

the CPU, and is contained in the PSW.

The interrupt priority control circuit performs interrupt control according to the contents of this flag as shown

in Table 6-3.

IST0 cannot be modified by 4-bit handling instructions or bit-handling instructions. IST0 is always set to 1 during

interrupt servicing. Therefore, it is not possible to write 0 to IST in the interrupt service routine which would result

in multiple interrupt.

After being saved to stack memory together with the rest of the PSW when an interrupt is acknowledged, IST0

is automatically set to 1. When an RETI instruction is executed, the original IST0 value (0) is restored.

A RESET input clears (0) the flag contents.

Table 6-3 IST0 Interrupt Servicing Status

Executing

Processing Status

Status 0

Status 1

IST0

0

1

CPU Processing

Normal program

processing in

progress

Interrupt servicing in

progress

Interrupt Requests of which

Acknowledgment is Possible

Acknowledgment of all interrupts

possible

Acknowledgment of all interrupts

disabled

After Interrupt

Acknowledgment

IST0

1

–

Contents

Main USER'S MANUAL PD75402A Page Page PREFACE USER OBJECTIVE COMPOSITION READING LEGEND Page Page Page Page CONTENTS OF FIGURES Fig. No Title Page Fig. No. Title Page Table No. Title Page CHAPTER 1. GENERAL 2 1.1 OUTLINE OF FUNCTIONS Page Page 5 1.4 BLOCK DIAGRAM PD75P402. Remarks Parentheses for the Page 7 (2) PROM mode PD75P402C/CT 8 1.5.2 44-Pin Plastic QFP ( 10mm) (1) Normal operating mode PD75P402s VPP is to be set to the GND potential. PD75P402 and the printed circuit board commonly in the Remarks Parentheses for the 9 (2) PROM mode CHAPTER 2. PIN FUNCTIONS 11 2.1 Remarks 1. In the PD75402A PIN FUNCTION LIST 2.1.1 Port Pin List Table 2-1 Port Pin List 12 2.1.2 List of Pins Other Than Port Pins Table 2-2 List of Pins Other than Port Pins PD75P402 and the printed circuit board commonly, the NC pin should be connected directly to VSS. Remarks For the status of each pin at reset, see CHAPTER 8 RESET FUNCTION. *If using the Page Page Page Page Page V V Type D P.U.R. P-ch P.U.R. enable IN P-ch N-ch V Type D V OUT data output disable P-ch IN/OUT data output disable IN/OUT data output disable Page CHAPTER 3. FEATURES OF ARCHITECTURE AND MEMORY MAP 22 Table 3-1 Data Memory Configuration and Address Range in Each Addressing Mode 23 Table 3-2 Addressing Mode List Page Page Page Page Page 29 Table 3-4 PD75402A I/O Map (1/2) Remarks 1. IE is an interrupt enable flag. 2. IRQ is an interrupt request flag. 30 Table 3-4 PD75402A I/O Map (2/2) CHAPTER 4. INTERNAL CPU FUNCTIONS ~ ~~ ~ Page Page Page Page Page 38 CHAPTER 4. INTERNAL CPU FUNCTIONS Fig. 4-8 Data Saved to Stack Memory Fig. 4-9 Data Restored from Stack Memory Page Page CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS Page 43 Fig. 5-2 Configuration of Ports 0 and 1 Page 45 Fig. 5-4 Configuration of Ports 2 and 6 Internal Bus Output Latch Page Page Page Page 50 Table 5-3 Operations with Input/Output Port Handling Instructions Page Page Page Page Page 56 Fig. 5-11 Processor Clock Control Register Format s) as CPU clock. Note When using a calue of fXX such that 4.19 MHz < fXX 5.0 MHz, if maximum speed mode : fXX/4 (PCC1, PCC0 = 11) is set as CPU clock frequency, 1 machine cycle is less than 0.95 Page Page Page Page Page Page Page Page Page Page () Page Page Page Page 72 Fig. 5-24 Serial Interface Block Diagram 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 109 Fig. 5-46 ACKD Operation (a) When ACK signal is output in 9th SCK clock interval Fig. 5-47 BSYE Operation (c) Clearing timing when transfer start directive is given during busy state (b) When ACK signal is output after 9th SCK clock interval HSCK SB0 111 Table 5-8 Signals in SBI Mode (2/2) 1 2 7 8 1 2 7 8 9 10 SB0 SCK Page 114 Fig. 5-49 Address Transmission form Master Device to Slave Device (WUP = 1) 115 Fig. 5-50 Command Transmission from Master Device to Slave Device 116 Fig. 5-51 Data Transmission from Master Device to Slave Device 117 Fig. 5-52 Data Transmission from Slave Device to Master Device Page Page Page Page Page Page Page CHAPTER 6. INTERRUPT FUNCTIONS 127 CHAPTER 6. INTERRUPT FUNCTIONS Fig. 6-1 Interrupt Control Circuit Block Diagram Page 6.3 INTERRUPT CONTROL CIRCUIT HARDWARE Page 131 CHAPTER 6. INTERRUPT FUNCTIONS Fig. 6-4 INT0 Noise Elimination Circuit Input/Output Timing Page Page Page Page Page Page Page Page CHAPTER 7. STANDBY FUNCTION Page Page Page CHAPTER 8. RESET FUNCTION 147 CHAPTER 8. RESET FUNCTION Table 8-1 State of Hardware after Reset *The contents of data memory addresses 038H to 03DH are made undefined by RESET input. CHAPTER 9. INSTRUCTION SET Page Page Page Page 153 2. Accumulator operation instructions 3. Increment/decrement instructions 4. Compare instructions () 154 Note Instruction Group Page Page 157 2. Accumulator operation instructions 3. Increment/decrement instructions 4. Compare instruction 158 2. Branch instructions 3. I/O instructions 4. CPU control instructions MOV A, #n4 MOV rp, #n8 MOV A, @HL MOV @HL, A MOV A, mem MOV XA, mem MOV mem, A MOV mem, XA XCH A, @HL XCH A, mem XCH XA, mem XCH A, reg1 MOVT XA, @PCXA ADDS A, #n4 ADDS A, @HL ADDC A, @HL AND A, @HL Page RORC A NOT A Page Page Page Page Page BR addr BR $addr BRCB !caddr CALLF !faddr RET RETS RETI PUSH rp POP rp Page IN A, PORTn OUT PORTn, A Page 177 PD75402A and PD75402A. Since the 178 179 The following development tools are available for system development using the ~ PD75402A: Language Processor PROM Writing Tools Page 181 Development Tool Configuration