9
FN8216.3
February 20, 2008
Principles of Operation
Control and Status Registers
The Control and Status Registers provide the user with a
mechanism for changing and reading the value of various
parameters of the X96012. The X96012 contains seven
Control, one Status, and several Reserved registers, each
being one Byte wide. (Figure 4). The Control registers
0 through 6 are located at memory addresses 80h through
86h respectively. The Status register is at memory address
87h, and the Reserved registers at memory address 88h
through 8Fh.
All bits in Control register 6 always power-up to the logic
state “0”. All bits in Control registers 0 through 5 power-up to
the logic state value kept in their corresponding nonvolatile
memory cells. The nonvolatile bits of a register retain their
stored values even when the X96012 is powered down, then
powered back up. The nonvolatile bits in Control 0 through
Control 5 registers are all preprogrammed to the logic state
“0” at the factory.
Bits indicated as “Reserved” are ignored when read, and
must be written as “0”, if any Write operation is performed to
their registers.
A detailed description of the function of each of the Control
and Status register bits follows:
Control Register 0
This register is accessed by performing a Read or Write
operation to address 80h of memory.
BL1, BL0: BLOCK LOCK PROTECTION BITS
(NON-VOLATILE)
These two bits are used to inhibit any write operation to
certain addresses within the memory array. The protected
region of memory is determined by the values of the two bits,
as shown in Table 1.
If the user attempts to perform a write operation to a
protected region of memory, the operation is aborted without
changing any data in the array.
Notice that if the Write Protect (WP
) input pin of the X96012
is active (LOW), then any write operation to the memory is
inhibited, irrespective of the Block Lock bit settings.
VRM: VOLTAGE REFERENCE PIN MODE (NON-VOLATILE)
The VRM bit configures the Voltage Reference pin (VREF)
as either an input or an output. When the VRM bit is set to
“0” (default), the voltage at pin VREF is an output from the
X96012’s internal voltage reference. When the VRM bit is
set to “1”, the voltage reference for the VREF pin is external.
See Figure 5.
ADCIN: A/D CONVERTER INPUT SELECT
(NON-VOLATILE)
The ADCIN bit selects the input of the on-chip A/D converter.
When the ADCIN bit is set to “0” (default), the output of the
on-chip temperature sensor is the input to the A/D converter.
When the ADCIN bit is set to “1”, the input to the A/D
converter is the voltage at the VSENSE pin. See Figure 7.
ADCFILTOFF: ADC FILTERING CONTROL
(NON-VOLATILE)
When this bit is “1”, the status register at 87h is updated after
every conversion of the ADC. When this bit is “0” (default),
the status register is updated after four consecutive
conversions with the same result, on the 6 MSBs.
NV1234: CONTROL REGISTERS 1, 2, 3 AND 4
VOLATILITY MODE SELECTION BIT (NON-VOLATILE)
When the NV1234 bit is set to “0” (default), bytes written to
Control registers 1, 2, 3, and 4 are stored in volatile cells,
and their content is lost when the X96012 is powered down.
When the NV1234 bit is set to “1”, bytes written to Control
registers 1, 2, 3, and 4 are stored in both volatile and
nonvolatile cells, and their value doesn’t change when the
X96012 is powered down and powered back up. See
“Writing to Control Registers” on page 20.
I1DS: CURRENT GENERATOR 1 DIRECTION SELECT BIT
(NON-VOLATILE)
The I1DS bit sets the polarity of Current Generator 1, DAC1.
When this bit is set to “0” (default), the Current Generator 1
of the X96012 is configured as a Current Source. Current
Generator 1 is configured as a Current Sink when the I1DS
bit is set to “1”. See Figure 8.
I2DS: CURRENT GENERATOR 2 DIRECTION SELECT BIT
(NON-VOLATILE)
The I2DS bit sets the polarity of Current Generator 2, DAC2.
When this bit is set to “0” (default), the Current Generator 2
of the X96012 is configured as a Current Source. Current
Generator 2 is configured as a Current Sink when the I2DS
bit is set to “1”. See Figure 8.
Control Register 1
This register is accessed by performing a Read or Write
operation to address 81h of memory. This byte’s volatility is
determined by bit NV1234 in Control register 0.
TABLE 1.
BL1
BL0
PROTECTED
ADDRESSES (SIZE)
PARTITION OF
ARRAY LOCKED
0 0 None (Default) None (Default)
0 1 00h to 7Fh (128 bytes) GPM
1 0 00h to 7Fh and 90h to CFh
(192 bytes)
GPM, LUT1
1 1 00h to 7Fh and 90h to 10Fh
(256 bytes)
GPM, LUT1, LUT2
X96012
