SCC UART Mode
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
21-24 Freescale Semiconductor
To receive S-records, the core must wait for an RX interrupt, indicating that a complete S-record buffer
was received. Transmission requires assembling S-records into buffers and linking them to the TxBD
table; transmission can be paused when an XOFF character is received. This scheme minimizes the
number of interrupts the core receives (one per S-record) and relieves it from continually scanning for
control characters.
XOFF E should be cleared; R should be set. Whenever the core receives a control-character-received (CCR)
interrupt and the RCCR contains XOFF, the software should immediately stop transmitting by setting
PSMR[FRZ]. This keeps the other station from losing data when it runs out of Rx buffers.
XON XON should be received after XOFF. E should be cleared and R should be set. PSMR[FRZ] on the
transmitter should now be cleared. The CPM automatically resumes transmission of the serial line at the
point at which it was previously stopped. Like XOFF, the XON character is not stored in the receive buffer.
Table21-14. UART Control Characters for S-Records Example (continued)
Character Description