UM10429
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User manual
Rev. 1 — 20 October 2010
96 of 258
NXP Semiconductors
UM10429
Chapter 11: LPC1102 SPI0 with SSP
11.6.7 SPI/SSP Raw Interrupt Status Register
This read-only register contains a 1 for each interrupt condition that is asserted,
regardless of whether or not the interrupt is enabled in the SSPIMSC registers.
11.6.8 SPI/SSP Masked Interrupt Status Register
This read-only register contains a 1 for each interrupt condition that is asserted and
enabled in the SSPIMSC registers. When an SPI interrupt occurs, the interrupt service
routine should read this register to determine the cause(s) of the interrupt.
Table 96:
SPI/SSP Interrupt Mask Set/Clear register (SSP0IMSC - address 0x4004 0014) bit
description
Bit
Symbol
Description
Reset
Value
0
RORIM
Software should set this bit to enable interrupt when a Receive
Overrun occurs, that is, when the Rx FIFO is full and another frame is
completely received. The ARM spec implies that the preceding frame
data is overwritten by the new frame data when this occurs.
0
1
RTIM
Software should set this bit to enable interrupt when a Receive
Time-out condition occurs. A Receive Time-out occurs when the Rx
FIFO is not empty, and no has not been read for a “time-out period".
The time-out period is the same for master and slave modes and is
determined by the SSP bit rate: 32 bits at PCLK / (CPSDVSR
×
[SCR+1]).
0
2
RXIM
Software should set this bit to enable interrupt when the Rx FIFO is at
least half full.
0
3
TXIM
Software should set this bit to enable interrupt when the Tx FIFO is at
least half empty.
0
31:4
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
NA
Table 97:
SPI/SSP Raw Interrupt Status register (SSP0RIS - address 0x4004 0018) bit
description
Bit
Symbol
Description
Reset Value
0
RORRIS
This bit is 1 if another frame was completely received while the
RxFIFO was full. The ARM spec implies that the preceding
frame data is overwritten by the new frame data when this
occurs.
0
1
RTRIS
This bit is 1 if the Rx FIFO is not empty, and has not been read
for a “time-out period". The time-out period is the same for
master and slave modes and is determined by the SSP bit
rate: 32 bits at PCLK / (CPSDVSR
×
[SCR+1]).
0
2
RXRIS
This bit is 1 if the Rx FIFO is at least half full.
0
3
TXRIS
This bit is 1 if the Tx FIFO is at least half empty.
1
31:4
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA