There are two ways to send a
block-start signal:
- Method 1: Deliberately
leave an idle time of ten bits or more by delaying the time between the
transmission of the last frame of data in the previous block and the
transmission of the address frame of the new block.
- Method 2: The SCI port
first sets the TXWAKE bit (SCICTL1, bit 3) to 1 before writing to the
SCITXBUF register. This sends an idle time of exactly 11 bits. In this
method, the serial communications line is not idle any longer than
necessary. (A don't care byte has to be written to SCITXBUF after setting
TXWAKE, and before sending the address, so as to transmit the idle
time.)