SN8F2280 Series
USB 2.0 Full-Speed 8-Bit Micro-Controller
The UART transfer format includes “Bus idle status”, “Start bit”, “8-bit Data”, “Parity bit” and “Stop bit” as following.
UART Transfer Format with Parity Bit
UART Transfer Format without Parity Bit
Bus Idle Status
The bus idle status is the bus non-operating status. The UART receiver bus idle status of MCU is floating status and
tied high by the transmitter device terminal. The UART transmitter bus idle status of MCU is high status. The UART bus
will be set when URXEN and UTXEN are enabled.
Start Bit
UART is a asynchronous type of communication and need a attention bit to offer receiver the transfer starting. The start
bit is a simple format which is high to low edge change and the duration is one bit period. The start bit is easily
recognized by the receiver.
8-bit Data
The data format is 8-bit length, and LSB transfers first following start bit. The one bit data duration is the unit of UART
baud rate controlled by register.
Parity Bit
The parity bit purpose is to detect data error condition. It is an extra bit following the data stream. The parity bit includes
odd and even check methods controlled by URXPS/UTXPS bits. After receiving data and parity bit, the parity check
executes automatically. The URXPC bit indicates the parity check result. The parity bit function is controlled by
URXPEN/UTXPEN bits. If the parity bit function is disabled, the UART transfer contents remove the parity bit and the
stop bit follows the data stream directly.
Stop Bit
The stop bit is like start bit using a simple format to indicate the end of UART transfer. The stop bit format is low to high
edge change and the duration is one bit period.
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