M38027E8SP Datasheet, PDF (20/51 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS
3802 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
Transmit or receive clock
Transmit buffer write
signal
TBE=0
TSC=0
TBE=1
Serial output TXD
ST
Receive buffer read
signal
TBE=0
D0
D1
1 start bit
7 or 8 data bit
1 or 0 parity bit
1 or 2 stop bit (s)
Serial input RXD
ST
D0
D1
TBE=1
SP
ST
D0
TSC=1^V
D1
SP
V _{Generated at 2nd bit in 2-stop-bit mode}
RBF=1
SP
ST
RBF=0
D0
D1
RBF=1
SP
Notes 1: Error flag detection occurs at the same time that the RBF flag becomes "1" (at 1st stop bit, during reception).
2: The transmit interrupt (TI) can be selected to occur when either the TBE or TSC flag becomes "1", depending on the setting of the transmit interrupt
source selection bit (TIC) of the serial I/O control register.
3: The receive interrupt (RI) is set when the RBF flag becomes "1".
4: After data is written to the transmit buffer when TSC=1, 0.5 to 1.5 cycles of the data shift cycle is necessary until changing to TSC=0.
Fig. 13 Operation of UART serial I/O function
Serial I/O1 control register (SIO1CON) 001A16
The serial I/O control register consists of eight control bits for the
serial I/O function.
UART control register (UARTCON) 001B16
The UART control register consists of four control bits (bits 0 to 3)
which are valid when asynchronous serial I/O is selected and set
the data format of an data transfer. One bit in this register (bit 4) is
always valid and sets the output structure of the P45/TXD pin.
Serial I/O1 status register (SIO1STS) 001916
The read-only serial I/O1 status register consists of seven flags
(bits 0 to 6) which indicate the operating status of the serial I/O
function and various errors.
Three of the flags (bits 4 to 6) are valid only in UART mode.
The receive buffer full flag (bit 1) is cleared to “0” when the receive
buffer is read.
If there is an error, it is detected at the same time that data is
transferred from the receive shift register to the receive buffer, and
the receive buffer full flag is set. A write to the serial I/O status reg-
ister clears all the error flags OE, PE, FE, and SE (bit 3 to bit 6, re-
spectively). Writing “0” to the serial I/O enable bit SIOE (bit 7 of
the Serial I/O Control Register) also clears all the status flags, in-
cluding the error flags.
All bits of the serial I/O1 status register are initialized to “0” at re-
set, but if the transmit enable bit (bit 4) of the serial I/O control reg-
ister has been set to “1”, the transmit shift completion flag (bit 2)
and the transmit buffer empty flag (bit 0) become “1”.
Transmit buffer/Receive buffer register (TB/
RB) 001816
The transmit buffer and the receive buffer are located at the same
address. The transmit buffer is write-only and the receive buffer is
read-only. If a character bit length is 7 bits, the MSB of data stored
in the receive buffer is “0”.
Baud rate generator (BRG) 001C16
The baud rate generator determines the baud rate for serial trans-
fer.
The baud rate generator divides the frequency of the count source
by 1/(n + 1), where n is the value written to the baud rate genera-
tor.
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