UPD78F9418A NEC, UPD78F9418A Datasheet - Page 192

• Manufacturer Part Number: UPD78F9418A
• Description: (UPD7894xxA) 8-Bit Single Chip Microcontrollers
• Manufacturer: NEC

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(b)
Parity types and operation
The parity bit is used to detect a bit error in the communication data. Normally, the same kind of parity
bit is used on the transmitting side and the receiving side. With even parity and odd parity, a “1” bit
(odd number) error can be detected. With 0 parity and no parity, an error cannot be detected.
(i)
(ii)
(iii) 0 Parity
(iv) No parity
Even parity
• • • • At transmission
• • • • At reception
Odd parity
• • • • At transmission
• • • • At reception
A parity bit is not added to the transmit data. At reception, data is received assuming that there is
no parity bit. Since there is no parity bit, a parity error does not occur.
When transmitting, the parity bit is set to 0 irrespective of the transmit data.
At reception, a parity bit check is not performed. Therefore, a parity error does not occur,
irrespective of whether the parity bit is set to 0 or 1.
The transmission operation is controlled so that the number of bits with a value of 1 in the
transmit data including the parity bit may be even. The parity bit value should be as follows.
The number of bits with a value of 1 is an odd number in transmit data:
The number of bits with a value of 1 is an even number in transmit data:
The number of bits with a value of 1 in the receive data including the parity bit is counted, and if
the number is odd, a parity error occurs.
Conversely to even parity, the transmission operation is controlled so that the number of bits
with a value of 1 in the transmit data including the parity bit may be odd. The parity bit value
should be as follows.
The number of bits with a value of 1 is an odd number in transmit data:
The number of bits with a value of 1 is an even number in transmit data:
The number of bits with a value of 1 in the receive data including the parity bit is counted, and if
the number is even, a parity error occurs.
CHAPTER 13 SERIAL INTERFACE 00
User’s Manual U13952EJ3V0UD
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