FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
NULL COMMANDS
This command is sent by sending binary 000x xxxx data. This can be used to read IC status in the SPI return word. Message
000x xx00 reads Status Register 0. Message 000x xx01 through 000x xx11 read additional internal registers.
Table 9. NULL Commands
SPI Data Bits
7
6
5
4
3
2
1
0
Write
0
0
0
x
x
x
0
0
Reset
NULL Commands are described in detail in the STATUS REGISTERS section of this document.
MASK Command
This is the mask for interrupts. A bit set to “1” enables the corresponding interrupt. Because of the number of MASK bits, this
register is in two portions:
1. MASK0
2. MASK1
Both are accessed with 0010 xxxx and 0011 xxxx patterns respectively. Figure 20 illustrates how interrupts are enabled and
faults cleared.
CLINT0 and CLINT1 have the same format as MASK0 and MASK1 respectively, but the action is to clear the interrupt latch
and status register 0 bit corresponding to the lower nibble of the command.
Table 10. MASK0 Register
SPI Data Bits
7
6
5
4
3
2
1
0
Write
0
0
1
0
x
x
x
x
Reset
1
1
1
1
INTERRUPT HANDLING
To Status Register
From MASKx:N Register
net N
INT Source
INT Clear
Fault
Various Faults
S
INT
Latch
From Clint Command
R
net 0
Figure 20. Interrupt Handling
Table 11. MASK1 Register
SPI Data Bits
7
6
5
4
3
2
1
0
Write
0
0
1
1
x
x
x
x
Reset
1
1
1
1
33937
Analog Integrated Circuit Device Data
Freescale Semiconductor
34
FREESCALE [ Freescale ]
