HT85F2270 datasheet(216/226 Pages) HOLTEK

216 / 226 page

Rev. 1.00

�16 of ��6

�a� 1�� 01�

Standard 8051 8-Bit Flash MCU

HT85F2260/HT85F2270/HT85F2280

UART1 Multiprocessor Communication

As UART1 can receive 9 bits in Mode A, it can be used for multiprocessor communication. When

the SM21 bit in the S1CON register is set, the receive interrupt is generated only when the 9th

received bit, the RB81 bit in the S1CON register, is high. Otherwise, no interrupt is generated upon

reception.

To utilise this feature for multiprocessor communication, the slave processors have their SM21 bit

set to high. The master processor transmits the slave’s address, with the 9th bit set high, generating

a reception interrupt in all of the slaves. The slave processors’ software compares the received byte

with their network address. If there is a match, the addressed slave clears its SM21 flag and the rest

of the message is transmitted from the master with the 9th bit set to low. The other slaves keep their

SM21 set high so that they ignore the rest of the message sent by the master. In this way, there are

reduced program overheads to distinguish the target slave MCU.

UART1 Baud Rate Setup

The UART1 operating Modes A and B, have a variable baud rate setup using the UART1 Baud

rate generator. The clock source is sourced from the system clock. The baud rate generator can be

controlled using the S1RELH and S1RELL registers and the clock is selected using the S1PRE0 and

S1PRE1 bits.

fSYS

10-bit Timer

S1RELH[1:0]

S1RELL[7:0]

UART1

Baud Rate

SP1CLK

fSYS/4

fSYS

fSYS/6

fSYS/1�

S1PRE0

S1PRE1

�

÷�

÷16

UART1 Baud Rate Generator

The Variable baud rate can be derived using the following equation:

)

(

])

[

(

CLK

Freq

REL

Rate

Baud

−

HT85F2270 bảng dữ liệu(PDF) 216 Page - Holtek Semiconductor Inc

HT85F2270 bảng dữ liệu(HTML) 216 Page - Holtek Semiconductor Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

bảng dữ liệu tải về

Link URL