Electronic Components Datasheet Search |
|
HT82A821R Datasheet(PDF) 6 Page - Holtek Semiconductor Inc |
|
HT82A821R Datasheet(HTML) 6 Page - Holtek Semiconductor Inc |
6 / 39 page HT82A821R Rev. 1.10 6 June 29, 2007 Program Memory - PROM 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 ´15 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 USB interrupt service program. If the USB interrupt 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 0 in- terrupt service program. If a timer interrupt results from a Timer/Event Counter 0 overflow, and if the in- terrupt is enabled and the stack is not full, the program begins execution at location 008H. · Location 00CH This location is reserved for the Timer/Event Counter 1 interrupt service program. If a timer interrupt results from a Timer/Event Counter 1 overflow, and the inter- rupt is enabled and the stack is not full, the program begins execution at location 00CH. · Table location Any location in the program memory can be used as look-up tables. There are three method to read the ROM data by two table read instructions: ²TABRDC² and ²TABRDL², 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 ta- ble is well-defined, the other bits of the table word are transferred to the lower portion of TBLH, and the re- maining 1-bit words are read as ²0². The Table Higher-order byte register (TBLH) is read only. The ta- ble pointer (TBLP, TBHP) is a read/write register (07H, 1FH), which indicates the table location. Before ac- cessing the table, the location must be placed in the TBLP and TBHP (If the OTP option TBHP is disabled, the value in TBHP has no effect). 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 should be disabled prior to the table read instruction. 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 require- ments. Stack Register - STACK This is a special part of the memory which is used to save the contents of the program counter only. The stack is organized into 16 levels and is neither part of the data nor part of the program space, and is neither read- able nor writeable. The activated level is indexed by the stack pointer (SP) and is neither readable nor writeable. At a subroutine call or interrupt acknowledge signal, the contents of the program counter are pushed onto the stack. At the end of a subroutine or an interrupt routine, 7 F F H n F F H P r o g r a m M e m o r y 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 0 0 8 H n 0 0 H 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 U S B I n t e r r u p t S u b r o u t i n e 0 0 4 H 0 0 0 H T i m e r / E v e n t C o u n t e r 0 I n t e r r u p t S u b r o u t i n e 0 0 C H T i m e r / E v e n t C o u n t e r 1 I n t e r r u p t S u b r o u t i n e 1 5 B i t s Program Memory 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 when TBHP is disabled @7~@0: TBLP bits TBHP register bit2~bit0 when TBHP is enabled |
Similar Part No. - HT82A821R |
|
Similar Description - HT82A821R |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |