HT36M4 datasheet(7/24 Pages) HOLTEK

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HT36M4

Rev. 1.10

March 14, 2007

· Bank pointer

The program memory is organized into 8 banks and

each bank into 8192

´16 of bits program ROM. PF2~

PF0 is used as the bank pointer. After an instruction

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. The new bank is only se-

lected after an instruction cycle is executed. When the

PF register is used to select the bank, the PF register

is write only. It is not until the following instruction has

completed execution that the bank will be actually se-

lected. It should be note that the PF register is write

only.

Wavetable ROM

The ST11~ST0 are used to defined the start address of

each sample on the wavetable and read the waveform

data from the location. HT36M4 provides 17 output ad-

dress lines from WA16~WA0, the ST11~ST0 are used

to locate the major 12 bits i.e. WA16~WA5 and the un-

defined data from WA4~WA0 are always set to 00000b.

So the start address of each sample have to be located

at a multiple of 32 bytes. Otherwise, the sample will not

be read out correctly because it has a wrong starting

code.

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 8 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 acknowledgment, the

contents of the program counter are pushed onto the

stack. At the end of a subroutine or an interrupt routine,

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 Stack Pointer 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

acknowledgment 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 subse-

quently executed, a stack overflow occurs and the first

entry will be lost (only the most recent eight return ad-

dress are stored).

Data Memory

- RAM

The data memory is designed with 2

´256´8 bits. The

data memory is divided into three functional groups:

special function registers, wavetable function register,

and general purpose data memory (2

´192´8). Most of

them are read/write, but some are read only.

S p e c i a l P u r p o s e

D a t a M e m o r y

0 0 H

0 1 H

0 2 H

0 3 H

0 4 H

0 5 H

0 6 H

0 7 H

0 8 H

0 9 H

0 A H

0 B H

0 C H

0 D H

0 E H

0 F H

1 0 H

1 1 H

1 2 H

1 3 H

1 4 H

1 5 H

1 6 H

1 7 H

1 8 H

1 9 H

1 A H

1 B H

1 C H

1 D H

1 E H

1 F H

2 0 H

2 1 H

2 2 H

2 3 H

2 4 H

2 5 H

2 6 H

2 7 H

2 9 H

2 A H

2 B H

3 F H

: U n u s e d .

R e a d a s " 0 0 "

I n d i r e c t A d d r e s s i n g R e g i s t e r 0

M P 0

I n d i r e c t A d d r e s s i n g R e g i s t e r 1

M P 1

A C C

P C L

T B L P

T B L H

W D T S

S T A T U S

I N T C

T M R 0 H

T M R 0 L

T M R 0 C

T M R 1 H

T M R 1 L

T M R 1 C

P A

P A C

P B

P B C

P F

D A H

C h a n n e l n u m b e r s e l e c t

F r e q u e n c y n u m b e r h i g h b y t e

F r e q u e n c y n u m b e r l o w b y t e

S t a r t a d d r e s s h i g h b y t e

S t a r t a d d r e s s l o w b y t e

R e p e a t n u m b e r h i g h b y t e

R e p e a t n u m b e r l o w b y t e

C o n t r o l r e g i s t e r

R i g h t v o l u m c o n t r o l

2 8 H

W a v e t a b l e F u n c t i o n

R e g i s t e r

D A L

D A C

B P

F F H

4 0 H

G e n e r a l P u r p o s e

D a t a M e m o r y

( 1 9 2

´ 2 B y t e s )

B a n k 0

B a n k 1

RAM Mapping

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