Datenblatt-Suchmaschine für elektronische Bauteile |
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HT82B40R Datenblatt(PDF) 9 Page - Holtek Semiconductor Inc |
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HT82B40R Datenblatt(HTML) 9 Page - Holtek Semiconductor Inc |
9 / 54 page HT82B40R/HT82B40A Rev. 1.70 9 November 5, 2014 in the TBLP and TBHP registers (if the configuration option has disabled TBHP then the value in TBHP has no effect). TBLH is read only and cannot be restored. If the main routine and the ISR (Interrupt Service Rou- tine) both employ the table read instruction, the con- tents of the TBLH in the main routine are likely to be changed by the table read instruction used in the ISR and errors can occur. Using the table read instruction in the main routine and the ISR simultaneously should be avoided. However, if the table read instruction has to be applied in both the main routine and the ISR, the interrupt should be disabled prior to the table read in- struction. It will not be enabled until the TBLH has been backed up. All table related instructions require two cycles to complete the operation. These areas may function as normal program memory depending on the requirements. Once TBHP is enabled, the instruction ²TABRDC [m]² reads the Program Memory data as defined by the TBLP and TBHP values. If the Program Memory code option has disabled TBHP, the instruction ²TABRDC [m] ² reads the Program Memory data as defined by TBLP only in the current Program Memory page. Look-up Table Any location within the Program Memory can be defined as a look-up table where programmers can store fixed data. To use the look-up table, the table pointer must first be setup by placing the lower order address of the look up data to be retrieved in the TBLP register and the higher order address in the TBHP register. These two registers define the full address of the look-up table. Using the TBHP must be selected by configuration op- tion, if not used table data can still be accessed but only the lower byte address in the current page or last page can be defined. After setting up the table pointers, the table data can be retrieved from the current Program Memory page or last Program Memory page using the ²TABRDC[m]² or ²TABRDL [m]² instructions, respectively. When these in- structions are executed, the lower order table byte from the Program Memory will be transferred to the user de- fined Data Memory register [m] as specified in the in- struction. The higher order table data byte from the Program Memory will be transferred to the TBLH special register. Any unused bits in this transferred higher order byte will be read as ²0². Table Program Example The following example shows how the table pointer and table data is defined and retrieved from the microcontroller. This example uses raw table data lo- cated in the last page which is stored there using the ORG statement. The value at this ORG statement is ²F00H² which refers to the start address of the last page within the 4K Program Memory of device. The table pointer is setup here to have an initial value of ²06H². This will ensure that the first data read from the data ta- ble will be at the Program Memory address ²F06H² or 6 locations after the start of the last page. Note that the value for the table pointer is referenced to the first ad- dress of the present page if the ²TABRDC [m]² instruc- tion is being used. The high byte of the table data which in this case is equal to zero will be transferred to the TBLH register automatically when the ²TABRDL [m]² in- struction is executed. P r o g r a m M e m o r y P r o g r a m C o u n t e r H i g h B y t e T B L P T B L H S p e c i f i e d b y [ m ] T a b l e C o n t e n t s H i g h B y t e T a b l e C o n t e n t s L o w B y t e Table Read - TBLP only P r o g r a m M e m o r y T B L H S p e c i f i e d b y [ m ] H i g h B y t e o f T a b l e C o n t e n t s L o w B y t e o f T a b l e C o n t e n t s T B L P T B H P Table Read - TBLP/TBHP |
Ähnliche Teilenummer - HT82B40R_14 |
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Ähnliche Beschreibung - HT82B40R_14 |
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