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HT48E30 Datasheet(PDF) 6 Page - Holtek Semiconductor Inc |
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HT48E30 Datasheet(HTML) 6 Page - Holtek Semiconductor Inc |
6 / 43 page HT48E30 Rev. 1.20 6 March 3, 2006 Instruction Table Location *10 *9 *8 *7 *6 *5 *4 *3 *2 *1 *0 TABRDC [m] P10 P9 P8 @7 @6 @5 @4 @3 @2 @1 @0 TABRDL [m] 1 1 1 @7 @6 @5 @4 @3 @2 @1 @0 Table Location Note: *10~*0: Table location bits P10~P8: Current program counter bits @7~@0: Table pointer bits In System Programming In system programming allows programming and repro- gramming of HT48EXX microcontroller on application circuit board, this will save time and money, both during development in the lab. Using a simple 3-wire interface, the ISP communicates serially with the HT48EXX microcontroller, reprogramming program memory and EEPROM data memory on the chip. Pin Name Function Description PA0 SDATA Serial data input/output PA4 SCLK Serial clock input RES RESET Device reset VDD VDD Power supply VSS VSS Ground ISP Pin Assignments Program Memory - ROM The program memory is used to store the program in- structions which are to be executed. It also contains data, table, and interrupt entries, and is organized into 2048 ´14 bits, addressed by the program counter and ta- ble pointer. Certain locations in the program memory are reserved for special usage: · Location 000H This area is reserved for program initialization. After a chip reset, the program always begins execution at lo- cation 000H. · Location 004H This area is reserved for the external interrupt service program. If the INT input pin is activated, the interrupt is enabled and the stack is not full, the program begins execution at location 004H. · Location 008H This area is reserved for the timer/event counter inter- rupt service program. If a timer interrupt results from a timer/event counter overflow, and if the interrupt is en- abled and the stack is not full, the program begins exe- cution at location 008H. · Table location Any location in the program memory space can be used as look-up tables. The instructions ²TABRDC [m] ² (the current page, one page=256 words) and ²TABRDL [m]² (the last page) transfer the contents of the lower-order byte to the specified data memory, and the higher-order byte to TBLH (08H). Only the destination of the lower-order byte in the table is well-defined, the other bits of the table word are trans- ferred to the lower portion of TBLH, and the remaining 2-bits words are read as ²0². The Table Higher-order byte register (TBLH) is read only. The table pointer (TBLP) is a read/write register (07H), which indicates the table location. Before accessing the table, the lo- cation must be placed in the TBLP. The TBLH is read only and cannot be restored. If the main routine and the ISR (Interrupt Service Routine) both employ the table read instruction, the contents of the TBLH in the main routine are likely to be changed by the table read instruction used in the ISR. Errors can occur. In other words, using the table read instruction in the main rou- tine 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 is supposed to 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 upon the requirements. 7 F F H n F F H P r o g r a m M e m o r y D e v i c e I n i t i a l i z a t i o n P r o g r a m E x t e r n a l I n t e r r u p t S u b r o u t i n e T i m e r / E v e n t C o u n t e r I n t e r r u p t S u b r o u t i n e L o o k - u p T a b l e ( 2 5 6 w o r d s ) L o o k - u p T a b l e ( 2 5 6 w o r d s ) N o t e : n r a n g e s f r o m 0 t o 7 n 0 0 H 0 0 8 H 0 0 4 H 0 0 0 H 1 4 b i t s 7 0 0 H Program Memory |
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Similar Description - HT48E30 |
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