HT83C51 datasheet(11/12 Pages) HONEYWELL

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HT83C51

PINOUT DIAGRAM

Vdd

P0.0 (AD0)

P0.1 (AD1)

P0.2 (AD2)

P0.3 (AD3)

P0.4 (AD4)

P0.5 (AD5)

P0.6 (AD6)

P0.7 (AD7)

EAn

ALE

PSENn

P2.7 (A15)

P2.6 (A14)

P2.5 (A13)

P2.4 (A12)

P2.3 (A11)

P2.2 (A10)

P2.1 (A9)

P2.0 (A8)

(T2) P1.0

(T2EX) P1.1

(ECI) P1.2

(CEXO) P1.3

(CEX1) P1.4

(CEX2) P1.5

(CEX3) P1.6

(CEX4) P1.7

RST

(RXD) P3.0

(TXD) P3.1

(INT0n) P3.2

(INT1n) P3.3

(T0) P3.4

(T1) P3.5

(WRn) P3.6

(RDn) P3.7

XTAL2

XTAL1

Vss

HT51

DIFFERENCES BETWEEN

INTEL 8XC51FC AND HT83C51

There are a few areas in which the HT51 differs from the

8XC51FC. These differences will be covered in this

appendix. In this discussion, 8XC51FC will be used

generically to refer to all speed grades of the Intel 8XC51FC

family, including the 16MHz 8XC51FC-1.

1. Reset

The 8XC51FC requires the RST input to be held high for at

least 24 oscillator periods to guarantee the reset is completed

in the chip. Also, the port pins are reset asynchronously as

soon as the RST pin is pulled high. On the HT51, all portions

of the chip are reset synchronously when the RST pin has

been high during 2 rising edges of the input clock.

When coming out of reset, the 8XC51FC takes 1 to 2

machine cycles to begin driving ALE and PSENn. The

HT51 will begin driving ALE and PSENn 2 oscillator periods

after the RST is removed but the access during the first

machine cycle after reset is ignored by the processor. The

second cycle will repeat the access and processing will

begin.

2. Power Off Flag

The Power Off Flag in the PCON register has not been

implemented in the HT51.

3. On Circuit Emulation

The On Circuit Emulation mode of operation in the 8XC51FC

has not been implemented in the HT51.

`4. Operating Conditions

The operating voltage range for the 8XC51FC is 5V

± 20%.

The operating temperature range is 0

° to 70°C. On the

HT51, the operating voltage range is 5V

± 10%. The full

speed operating temperature range is -55

° to +225°C;

typically, parts will operate up to +300

°C for a year, with

derated performance.

5. DC Characteristics

VIL min for the 8XC51FC is -0.5V for all inputs except EAn

which has a VIL min of 0V. The HT51 has a VIL min for all

inputs of Vss-0.3V.

6. Internal Program Memory

The 8XC51FC contains 32 Kbytes of internal program

ROM (83C51FC) or EPROM (87C51FC). The HT51

contains 8 Kbytes of internal program ROM.

7. Serial Communications

There is a chance the part will miss hardware interrupts

when performing full-duplex (simultaneous send and

receive) communication or when using the capture or

compare modes in the Programmable Counter Array (PCA).

As a result, the HT83C51 supports half-duplex operation.

Full duplex operation is not supported without additional

external hardware. Several acceptable work-around pro-

cedures have been identified for the problem associated

with the PCA.

PROGRAMMING THE MASK ROM

The HT83C51 has 8K bytes of on-chip mask program-

mable ROM. The part is usable with or without this memory

space personalised. Once the designer’s code has been

finalized, the ROM information can be transmitted to Hon-

eywell for metal programming of these memory locations.

A non-recurring fee is required to personalize the ROM and

a quantity purchase commitment fulfilled.

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