HT36A2 datasheet(7/24 Pages) HOLTEK

7 / 24 page

HT36A2

Rev. 1.00

June 19, 2003

other type is for wavetable code, which is addressed by

the start address ST11~0. On the program type,

WA15~0= PF2~0

´ 213+ PC12~0. On the wave table

ROM type, WA15~0=ST11~0

´ 25.

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

8192

´16 bits, addressed by the bank pointer, program

counter and table pointer.

Certain locations in the program memory of each bank

are reserved for special usage:

· Location 000H on bank0

This area is reserved for the initialization program. Af-

ter chip reset, the program always begins execution at

location 000H on bank0.

· Location 008H

This area is reserved for the Timer Counter 0 interrupt

service program on each bank. If timer interrupt results

from a timer counter 0 overflow, and if the interrupt is

enabled and the stack is not full, the program begins ex-

ecution at location 008H corresponding to its bank.

· Location 00CH

This area is reserved for the Timer Counter 1 interrupt

service program on each bank. If a timer interrupt re-

sults from a Timer Counter 1 overflow, and if the inter-

rupt is enabled and the stack is not full, the program

begins execution at location 00CH corresponding to

its bank.

· Table location

Any location in the ROM space can be used as

look-up tables. The instructions TABRDC [m] (the cur-

rent page, 1 page=256 words) and TABRDL [m] (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

higher-order byte of the table word are transferred to

the TBLH. The Table Higher-order byte register

(TBLH) is read only. The Table Pointer (TBLP) is a

read/write register (07H), which indicates the table lo-

cation. Before accessing the table, the location must

be placed in 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 instruc-

tion, 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 this case, using the ta-

ble read instruction in the main routine and the ISR si-

multaneously 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 dis-

abled prior to the table read instruction. It will not be

enabled until the TBLH has been backed up. All table

related instructions need 2 cycles to complete the op-

eration. These areas may function as normal program

memory depending upon user requirements.

· Bank pointer

The program memory is organized into 8 banks and

each bank into 8192

´ 16 bits of program ROM.

PF[2~0] is used as the bank pointer. After an instruc-

tion has been executed to write data to the PF register

to select a different bank, note that the new bank will

not be selected immediately. It is not until the following

instruction has completed execution that the bank will

be actually selected. It should be note that the PF reg-

ister has to be cleared before setting to output mode.

Wavetable ROM

The ST[11~0] is used to defined the start address of

each sample on the wavetable and read the waveform

data from the location. HT36A2 provides 16 output ad-

dress lines from WA[15~0], the ST[11~0] is used to lo-

Instruction(s)

Table Location

*12

*11

*10

TABRDC [m]

P12

P11

P10

TABRDL [m]

11111

Table location

Note:

*12~*0: Bits of table location

@7~@0: Bits of table pointer

P12~P8: Bits of current Program Counter

0 0 0 0 H

0 0 0 8 H

T i m e r 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

P r o g r a m

R O M

1 6 b i t s

L o o k - u p t a b l e ( 2 5 6 w o r d s )

n 0 0 H

L o o k - u p t a b l e ( 2 5 6 w o r d s )

1 F F F H

N o t e : n r a n g e s f r o m 0 0 t o 1 F .

n F F H

T i m e r 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

0 0 0 C 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

Program memory for each bank

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