Motorola MPC533 Reference Manual page 672

SCI Queue Operation
Table 15-33. QSCI1SR Bit Descriptions (continued)
Bits Name
4 QTHF Receiver queue top-half full. QTHF is set when the receive queue locations SCRQ[0:7] are
completely filled with new data received via the serial shifter. QTHF is cleared when register
QSCI1SR is read with QTHF set, followed by a write of QTHF to zero.
0 = The queue locations SCRQ[0:7] are partially filled with newly received data or is empty
1 = The queue locations SCRQ[0:7] are completely full of newly received data
5 QBHF Receiver queue bottom-half full. QBHF is set when the receive queue locations SCRQ[8:15] are
completely filled with new data received via the serial shifter. QBHF is cleared when register
QSCI1SR is read with QBHF set, followed by a write of QBHF to zero.
0 = The queue locations SCRQ[8:15] are partially filled with newly received data or is empty
1 = The queue locations SCRQ[8:15] are completely full of newly received data
6 QTHE Transmitter queue top-half empty. QTHE is set when all the data frames in the transmit queue
locations SCTQ[0:7] have been transferred to the transmit serial shifter. QTHE is cleared when
register QSCI1SR is read with QTHE set, followed by a write of QTHE to zero.
0 = The queue locations SCTQ[0:7] still contain data to be sent to the transmit serial shifter
1 = New data may now be written to the queue locations SCTQ[0:7]
7 QBHE Transmitter queue bottom-half empty. QBHE is set when all the data frames in the transmit queue
locations SCTQ[8:15] has been transferred to the transmit serial shifter. QBHE is cleared when
register QSCI1SR is read with QBHE set, followed by a write of QBHE to zero.
0 = The queue locations SCTQ[8:15] still contain data to be sent to the transmit serial shifter
1 = New data may now be written to the queue locations SCTQ[8:15]
8:11 QRPNT Queue receive pointer. QRPNT is a 4-bit counter used to indicate the position where the next valid
data frame will be stored within the receive queue. This field is writable in test mode only;
otherwise it is read-only.
12:15 QPEND Queue pending. QPEND is a 4-bit decrementer used to indicate the number of data frames in the
queue that are awaiting transfer to the SC1DR. This field is writable in test mode only; otherwise
it is read-only. From 1 (QPEND = 0b0000) to 16 (or done, QPEND = 1111) data frames can be
specified.
15-66
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
Description
MPC533 Reference Manual MOTOROLA