P80C31 View Datasheet(PDF) - Philips Electronics
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P80C31 Datasheet PDF : 38 Pages
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Philips Semiconductors
80C51 8-bit microcontroller family
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
Product specification
80C51/87C51/80C31
and 1 and exclude Slave 2 use address 1110 0100, since it is
necessary to make bit 2 = 1 to exclude slave 2.
The Broadcast Address for each slave is created by taking the
logical OR of SADDR and SADEN. Zeros in this result are trended
as don’t-cares. In most cases, interpreting the don’t-cares as ones,
the broadcast address will be FF hexadecimal.
Upon reset SADDR (SFR address 0A9H) and SADEN (SFR
address 0B9H) are leaded with 0s. This produces a given address
of all “don’t cares” as well as a Broadcast address of all “don’t
cares”. This effectively disables the Automatic Addressing mode and
allows the microcontroller to use standard 80C51 type UART drivers
which do not make use of this feature.
SCON Address = 98H
Bit Addressable
SM0/FE SM1
SM2
REN
TB8
RB8
Tl
Bit:
7
6
5
4
3
2
1
(SMOD0 = 0/1)*
Reset Value = 0000 0000B
Rl
0
Symbol Function
FE
SM0
SM1
Framing Error bit. This bit is set by the receiver when an invalid stop bit is detected. The FE bit is not cleared by valid
frames but should be cleared by software. The SMOD0 bit must be set to enable access to the FE bit.
Serial Port Mode Bit 0, (SMOD0 must = 0 to access bit SM0)
Serial Port Mode Bit 1
SM0 SM1 Mode
Description Baud Rate**
0
0
0
1
1
0
1
1
0
shift register
fOSC/12
1
8-bit UART
variable
2
9-bit UART
fOSC/64 or fOSC/32
3
9-bit UART
variable
SM2
Enables the Automatic Address Recognition feature in Modes 2 or 3. If SM2 = 1 then Rl will not be set unless the
received 9th data bit (RB8) is 1, indicating an address, and the received byte is a Given or Broadcast Address.
In Mode 1, if SM2 = 1 then Rl will not be activated unless a valid stop bit was received, and the received byte is a
Given or Broadcast Address. In Mode 0, SM2 should be 0.
REN
Enables serial reception. Set by software to enable reception. Clear by software to disable reception.
TB8
The 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software as desired.
RB8
In modes 2 and 3, the 9th data bit that was received. In Mode 1, if SM2 = 0, RB8 is the stop bit that was received.
In Mode 0, RB8 is not used.
Tl
Transmit interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or at the beginning of the stop bit in the
other modes, in any serial transmission. Must be cleared by software.
Rl
Receive interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or halfway through the stop bit time in
the other modes, in any serial reception (except see SM2). Must be cleared by software.
NOTE:
*SMOD0 is located at PCON6.
**fOSC = oscillator frequency
SU00043
Figure 7. SCON: Serial Port Control Register
2000 Jan 20
15
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