Receiving and sending data of SCI adopt and does not belong to a data form, include specifically:
One starts the location.
1- 8 data.
An strange / even check-up location can be chosen .
1 or 2 stop the location.
Distinguish data and additional location of address ‘ Exist only in the location mode of the address .
The elementary cell of the data is called the character, 1- 8 are long that it has. Each character includes one’s starting the location, 1 or 2 to stop the location, optional odd-even check-up location and address location. In SCI communicates, the data character with form information calls the frame.
Typical SCI data frame form of Fig. 1
Can use SCICCR register to dispose the data form adopted in SCI communication, the definition of controlling every function of the register that the table classifies as.
The table SCICCR register function is defined
SCI asynchronous communication adopts half a duplexing or all duplexing communication ways. The data frame of SCI includes an initial location, 1- 8′s data location, an available odd-even check-up location and 1 or 2 to stop the location, . Take up clock cycle of 8 SCICLKs each data location.
Fig. 2 SCI asynchronous communication form
The receiver begins to work after receiving an initial location, 4 pieces of continuous SCICLK low level of cycle show the effective initial location, . Without continuous 4 pieces of SCICLK low level of cycle, deal with and think highly of and look for another initial location newly.
As to the one behind of initial location of SCI data frame, the processor is sampled in the middle of each person 3 times, confirm the value of the location. Sampled point 3 times is in the 4th, the 5th and 6th SCICLK cycle separately, 3 values that 2 same values get and receive the location finally while sampling. Fig. 2 provides the detection of initial location of the asynchronous communication form, and provide and position sample of value of the location behind the initial location.
Because the receiver uses frames to move ahead simultaneously, the outside is sent and does not need to use the serial synchronous clock with the receiver, the clock is offered by device.