12
12-17
Serial I/O
12.2 Serial I/O Related Registers
32180 Group User's Manual (Rev.1.0)
•
When transmitting
If the attribute (odd/even) represented by the
number of 1's in data bits agrees with the selected
parity attribute, a parity bit "0" is added. If the
attribute (odd/even) represented by the number of 1's
in data bits does not agree with the selected parity
attribute, a parity bit "1" is added.
b7 b6 b5 b4 b3 b2 b1 b0
PAR S P
ST
Attribute derived from b7 + b6 + ... + b0
If it agrees with the selected
parity attribute, PAR = "0" is added.
If it does not agree with the selected
parity attribute, PAR = "1" is added.
LSB MSB
•
When receiving
The received data is checked to see if the number of
1's included in its data and parity bits agrees with
the parity attribute (known as parity check).
b7 b6 b5 b4 b3 b2 b1 b0
PAR S P
ST
LSB
MSB
If the result of b7 + b6 + ... + b0 + PAR does not agree
with the selected parity attribute, a parity error is assume
Notes : • Shown above is an example of a data format in 8-bit UART mode.
• The data bit numbers (bn) above indicate bit numbers in a data list, and not the register bit numbers (bn).
b8 b7 b6
b5
b4
b3
b2 b1
PAR S P
ST
b0
•
9-bit UART mode
b7 b6 b5
b4
b3
b2
b1 b0
PAR S P
ST
•
8-bit UART mode
b6 b5 b4
b3
b2
b1
b0
PAR S P
ST
(Note 1)
•
7-bit UART mode
b7 b6 b5
b4
b3
b2
b1
•
Clock-synchronous mode
b0
Note 1: Whether or not to add a parity bit is selectable.
Note 2: The stop bit can be chosen to be one bit or two bits long.
Direction of transfer
ST : Start bit PAR : Parity bit : One frame equivalent
b : Data bits SP : Stop bit
(Note 2)
(Note 1)
(Note 1)
(Note 2)
(Note 2)
Figure 12.2.7 Data Format When Parity is Enabled
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