Information

Serial Peripheral Interface
MPC8308 PowerQUICC II Pro Processor Reference Manual, Rev. 1
Freescale Semiconductor 19-11
‘1’. Writing ‘0’ has no effect. Setting a bit in the SPI mask register (SPIM) enables, and clearing a bit
masks the corresponding interrupt. Unmasked SPIE bits must be cleared before the core clears internal
interrupt requests. Figure 19-7 shows SPI event register.
Table 19-5 describes the SPIE fields.
19.3.1.3 SPI Mask Register (SPIM)
The SPI mask register (SPIM), shown in Figure 19-8, enables/masks interrupts for events that are
recognized by the SPI. When an event is recognized, the SPI sets the corresponding SPIE bit. Setting a
Offset 0x024 Access: Mixed
0 161718192021222324 31
R — LT DNR OV UN MME NE NF —
W
w1c w1c w1c w1c w1c
Reset All zeros
Figure 19-7. SPIE—SPI Event Register Definition
Table 19-5. SPIE Field Descriptions
Bits Name Description
0–16 — Reserved, should be cleared.
17 LT Last character was transmitted.
The last character is transmitted and new data can be written to SPID for further transmission.
18 DNR Note: Data not ready. In slave mode only when SPISEL
is asserted before data is ready in the SPI, IDLE is
sent on the line and UN bit is also asserted the SPI should be disable to restart its operation.
19 OV Slave/master overrun.
Indicates whether an overrun has occurred during reception.
In case of overrun the SPI continues transmission/reception process while reporting overrun for the missing
characters.
20 UN Slave underrun. Indicates whether the SPI transmitter did not have data to transmit on time, and therefore,
whether IDLE was sent on the line. Valid only in slave mode (SPMODE[M/S]) = 0.
In master mode (SPMODE[M/S]) = 1) if the SPI’s transmitter has no valid data to transmit the SPICLK stop
toggling and transmission/reception is frozen (no underrun is reported), when data is written to the SPITD the
transmission resumes.
21 MME Multiple-master error. Set when SPISEL
is asserted externally while the SPI is in master mode. Note that the
MME error can occur in loopback mode.
22 NE Not empty. When set Indicates that SPIRD contains a received character.
0 The receiver is empty
1 The receiver has valid received data and indications about LST (command register) and OV (SPIE).The
core is free to read the content of the receiver. Reading the receiver SPIRD clears NE if no more data is
available.
23 NF Not full. Indicates whether SPITD is not in use and a new character can be written to it by the core.
0 The transmitter is full.
1 The transmitter is not full. The core is free to write to the transmitter. NF must be clear to enable the
transmission of another character (writing to the transmitter clears NF)
24–31 — Reserved. Should be cleared.