HT82A821R_07 HOLTEK [Holtek Semiconductor Inc], HT82A821R_07 Datasheet - Page 7

• Manufacturer Part Number: HT82A821R_07
• Description: USB Audio MCU
• Manufacturer: HOLTEK [Holtek Semiconductor Inc]

signaled by a return instruction (RET or RETI), the pro-
gram counter is restored to its previous value from the
stack. After a chip reset, the SP will point to the top of the
stack.
If the stack is full and a non-masked interrupt takes
place, the interrupt request flag will be recorded but the
acknowledge signal will be inhibited. When the stack
pointer is decremented (by RET or RETI), the interrupt
will be serviced. This feature prevents stack overflow al-
lowing the programmer to use the structure more easily.
In a similar case, if the stack is full and a CALL is sub-
sequently executed, stack overflow occurs and the first
entry will be lost (only the most recent 16 return ad-
dresses are stored).
Data Memory - RAM
The data memory (RAM) is designed with 192 8 bits.
The data memory is divided into two functional groups:
namely; special function registers 54 8 bits and general
purpose data memory, Bank0: 192 8 bits. Most are
read/write, but some are read only.
The special function registers include the indirect ad-
dressing registers (R0;00H, R1;02H), Bank register (BP,
04H), Timer/Event Counter 0 higher order byte register
(TMR0H;0CH), Timer/Event Counter 0 lower order byte
register (TMR0L;0DH), Timer/Event Counter 0 control
register (TMR0C;0EH), Timer/Event Counter 1 higher
order byte register (TMR1H;0FH), Timer/Event Counter
1 lower order byte register (TMR1L;10H), Timer/Event
Counter 1 control register (TMR1C;11H), program coun-
ter lower-order byte register (PCL;06H), memory pointer
r e g i s t e r s ( M P 0 ; 0 1 H , M P 1 ; 0 3 H ) , a c c u m u l a t o r
(ACC;05H), table pointer (TBLP;07H, TBHP;1FH), table
higher-order byte register (TBLH;08H), status register
( S TAT U S ; 0 A H ) ,
(INTC0;0BH), Watchdog Timer option setting register
(WDTS;09H), I/O registers (PA;12H), I/O control regis-
ters (PAC;13H). Digital Volume Control Register
(USVC;1CH). USB status and control register
(USC;20H), USB endpoint interrupt status register
(USR;21H), system clock control register (UCC;22H).
Address and remote wakeup register (AWR;23H),
STALL register(24H), SIES register (25H), MISC regis-
ter(26H), SETIO register(27H), FIFO0~FIFO2 register
(28H~2AH). DAC_Limit_L register (2DH), DAC_Limit_H
register (2EH), DAC_WR register (2FH).
The remaining space before the 40H is reserved for fu-
ture expanded usage and reading these locations will
get 00H . The general purpose data memory, ad-
dressed from 40H to FFH, is used for data and control
information under instruction commands.
All of the data memory areas can handle arithmetic,
logic, increment, decrement and rotate operations di-
rectly. Except for some dedicated bits, each bit in the
Rev. 1.10
i n t e r r u p t
c o n t r o l
r e g i s t e r 0
7
data memory can be set and reset by SET [m].i and
memory pointer registers (MP0 or MP1).
CLR [m].i . They are also indirectly accessible through
RAM Mapping
HT82A821R
June 29, 2007