Using the Data EEPROM in the HT66Fxx

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1 Using the Data EEPROM in the HT66Fxx D/N: AN0191E Introduction The HT66Fxx series device contains an area of internal EEPROM Data Memory. The following gives a description about the EEPROM Data Memory using the HT66F40. Operation Principle The read/write function of the EEPROM in the HT66Fxx series device can be easily carried out by setting corresponding values to its related registers. There are three relevant registers: the address register EEA [41H], the data register EED [42H] and the control register EEC [140H], among which the EEA register and the EED register are located in BANK0, while the EEC register is located in BANK1. The EEA register is used for setting the address to be written to or read from the EEPROM. The EED register is used for the data that is to be written to the EEPROM or to save the data being read in the read mode. The EEC register is the EEPROM read/write control register and is located in BANK1 and needs to be operated using indirect addressing using the Indirect Address register, IAR1, and the Memory Pointer register, MP1. The following depicts the steps of the EEPROM read/write function: 1. Set the address to be read or written to the EEA register. 2. Set the data value to be written to the EED register (only in the write mode.) 3. Set the BP.0 to 1 to operate in BANK1. 4. Set the MP1 Memory Pointer to point to the EEC register of the EEPROM. 5. Set the read/write enable mode. 6. Set the read/write operation. 7. Wait for the completion of the read/write operation. 8. After the operations, the RD bit in the read mode or WT bit in the write mode will be cleared automatically to zero. Data read from the read mode is stored in the EED register where the interrupt require flag DEF will be set as 1. 1

2 Program Examples Two program examples are provided as follows. Example 1 is used to execute a read/write operation to the EEPROM using direct addressing. The description is mainly focused on how to setup the address register, the data register and the single control register to implement the read/write operation. Example 2 is used to execute a read/write operation using interrupts, which shows the way to implement a read/write function by setting the relevant interrupt registers and then enter the interrupt service routine. Example<1> : Read/Write EEPROM using a polling method ; Program name : EEPROM write and read mode (write_read.asm) ; Object : write data into the EEPROM and read out for comparison ; EEPROM interrupt : Disable ; Option : no demand ; Program list : #INCLUDE HT66F40.INC --- DATA.SECTION 'DATA' ADDR_TEMP DB? ; FEEPROM address variable DATA_TEMP DB? ; EPROM data variable CODE.SECTION 'CODE' ORG 00H JMP MAIN ORG 04H ; external interrupt 0 entry ORG 08H ; external interrupt 1 entry ORG 0CH ; comparator 0 interrupt entry ORG 010H ; comparator 0 interrupt entry ORG 014H ; CTM/STM CCRP or CCRA compare match interrupt entry ORG 018H ; ETM CCRP, CCRA or CCRB compare match interrupt entry ORG 01CH ; A/D interrupt entry ORG 020H ; SPI/I2C or external peripheral interrupt entry ORG 024H ; Time base 0 interrupt entry ORG 028H ; Time base 1 interrupt entry ORG 02CH ; LVD or EEPROM write/read interrupt entry ORG 30H MAIN: CLR PAC ; PA output ; PC output SET PAPU 2

3 SET PCPU CLR INTC0 ; disable interrupt MOV A,01H MOV SMOD,A ; set the system frequency as FH MOV A,0AH MOV WDTC,A ; disable WDT MOV CP0C,A MOV CP1C,A MOV ACERL,A MOV SCOMC,A WRITE_EEPROM: ; write mode ; set the address of the data to be written MOV A,055H MOV DATA_TEMP,A ; set the written data value -- ;EEPROM writing module -- WRITE_EEPROM_LOOP: MOV A,DATA_TEMP MOV EED,A SET IAR1.3 ; enable write SET IAR1.2 ; start writing WRITE_WAIT: SZ IAR1.2 ; wait for write completion, then clear WT to zero automatically JMP WRITE_WAIT NOP ; write completed NOP NOP CLR BP.0 CLR EEA CLR EED READ_EEPROM: ; read mode ; set the address of the data to be read ;FEEPROM reading module -- READ_EEPROM_LOOP: SET IAR1.1 ; enable read SET IAR1.0 ; start reading READ_WAIT: SZ IAR1.0 ; wait for read completion, and then clear RD to zero automatically JMP READ_WAIT MOV A, EED ; read completed, save the data to the EED register XOR A, DATA_TEMP ; compare the read/write data, and check if correct 3

4 SZ ACC ; false - output PC waveform CPL PA ; correct output PA waveform JMP WRITE_EEPROM FAIL: INC PC Program Description These examples depict the way to implement read/write operations to the EEPROM. In the description, a simple read and write operation to one address and data of the EEPROM is provided. The operating result will be compared with the value read from the EEPROM after writing 055H to [00H] of the EEPROM. If the values are the same, the PA port will output the waveform or else the PC port will output the waveform. Users can directly apply the writing or reading operation modules to their applications with some modifications to the ADDR_TEMP and DATA_TEMP. If more data reading and writing is required, call the operating module as a subroutine and modify the ADDR_TEMP and DATA_TEMP to be written and read. The operating method is as follows. Writing Module : write_eeprom_loop: mov a,addr_temp mov eea,a ; set the write data address mov a,data_temp mov eed,a ; set the write data value set bp.0 mov a,40h mov mp1,a set IAr1.3 ; enable write set IAr1.2 ; start writing WRITE_WAIT: sz IAr1.2 ; wait for write completion and then clear WT to zero automatically jmp WRITE_WAIT ret Reading Module: read_eeprom_loop: mov a,addr_temp mov eea,a ; set the write data address set bp.0 mov a,40h mov mp1,a set IAr1.1 ; enable read set IAr1.0 ; start reading READ_WAIT: sz IAr1.0 ; wait for read completion and then clear RD to zero automatically jmp READ_WAIT mov a, eed ; reading completed, save the data to the EED register ret 4

5 Example< 2> : EEPROM read/write operation using interrupts ; Program Name : enable EEPROM read/write mode interrupt (write_int.asm) ; Object : read/write operation to EEPROM with interrupts ; EEPROM interrupt : Enable ; Option: no demand ; Program List: #INCLUDE HT66F40.INC --- DATA.SECTION 'DATA' ADDR_TEMP DB? ; EEPROM address variable DATA_TEMP DB? ; EEPROM data variable TEMP DB? ; variable EEPROM_INT_FLAG DBIT ; interrupt flag CODE.SECTION 'CODE' ORG 00H JMP MAIN ORG 04H ; external interrupt0 entry ORG 08H ; external interrupt1 entry ORG 0CH ; comparator0 interrupt entry ORG 010H ; comparator1 interrupt entry ORG 014H ; CTM/STM CCRP or CCRA compare match interrupt entry ORG 018H ; ETM CCRP, CCRA or CCRB compare match interrupt entry ORG 01CH ; A/D interrupt entry ORG 020H ; SPI/I2C or external peripheral interrupt entry ORG 024H ; Time base 0 interrupt entry ORG 028H ; Time base 1 interrupt entry ORG 02CH ; LVD or EEPROM write/read 中斷入口 JMP EEPROM_INTERRUPT ORG 30H MAIN: CLR PAC ; PA output ; PC output SET PAPU SET PCPU CLR INTC0 ; disable interrupt MOV A,01H MOV SMOD,A ; set the system frequency as FH MOV A,0AH MOV WDTC,A ; disable WDT MOV CP0C,A MOV CP1C,A MOV ACERL,A MOV SCOMC,A SET EMI ; enable master interrupt SET DEE ; enable EEPROM interrupt 5

6 SET MF3E ; enable multi-function interrupt CLR DEF ; initialize interrupt request bit CLR EEPROM_INT_FLAG ; initialize flag -- WRITE_EEPROM: ; write mode ; set the write data address MOV A,055H MOV DATA_TEMP,A ; set the write data value -- ; EEPROM writing module ; WRITE_EEPROM_LOOP: MOV A,DATA_TEMP MOV EED,A SET IAR1.3 ; enable write SET IAR1.2 ; start writing WRITE_WAIT: SNZ EEPROM_INT_FLAG ; decide if the interrupt service routine is finished JMP WRITE_WAIT CLR EEPROM_INT_FLAG CLR TEMP READ_EEPROM: ; read mode ; set the address of the data to be read ; EEPROM reading module ;F READ_EEPROM_LOOP: SET IAR1.1 ; enable read SET IAR1.0 ; start reading READ_WAIT: SNZ EEPROM_INT_FLAG ; decide if the interrupt service routine has finished JMP READ_WAIT CLR EEPROM_INT_FLAG MOV A, TEMP ; this variable is the data being read XOR A, DATA_TEMP ; compare the read and write value SZ ACC ; false, PC outputs waveform CPL PA ; correct, PA outputs waveform JMP WRITE_EEPROM FAIL: INC PC EEPROM_INTERRUPT: ; EEPROM interrupt subroutine SET EEPROM_INT_FLAG 6

7 MOV A,EED ; save variables to the data being read MOV TEMP,A CLR DEF ; clear interrupt request flag by software for the next interrupt to be generated Program Description This example depicts how an EEPROM interrupt is generated and how its interrupt service routine is executed. When setting an EEPROM interrupt, there are three related control bits which must be set. These are it. Once an interrupt is generated, the interrupt require flag DEF will be set to 1 which will not be changed automatically to zero after entering the interrupt service routine. To ensure proper generation of following interrupts, it is necessary to clear the DEF bit to zero using the application program. The example here continuously writes 55H to one of the addresses in the EEPROM and compares it with the data values being read from the EEPROM. The interrupt request flag DEF will be set to 1 at every completion of a data read/write operation which will then generate an interrupt and then enter an interrupt service routine. Special Notes 1. To execute an EEPROM write operation, when using indirect addressing to setup the EEC register, first set the WTEN bit before setting the WT bit, in that order. 2. The EEC register, being located in BANK1, can only be setup using indirect addressing. 3. After an interrupt is generated, the system will not automatically clear the interrupt request flag DEF to zero. This must be executed using the application program to enable the next interrupt to be generated. During this process, read-only or write-only is allowed. In the write mode, the system will automatically erase the previous write operation. 7

Read and Write Control of the HT1380

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