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Analog-to-Digital Converter/Brownout Detector
LH75400/01/10/11 (Preliminary) User’s Guide
23-18
6/25/03
23.3.2.8 General Status Register
GS is the General Status Register. In this Read Only register, the 4-bit signal CBSTATE
field shows the current state of the Control Bank state machine. The CBTAG signal con-
tains the control bank entry number of the conversion that is taking place.
NOTE:
*If the Idle state is configured to bias a 4-wire Touch Screen for Pen IRQ detect, and if the pen is held
down, bit [8] is set if the state machine is in the GET_DATA state (Status Register contains 0x120).
To resolve this situation set up the measurement sequence for coordinate measurements. Have the
first measurement in the sequence and the last measurement in the sequence measure the analog
voltage the Pen Detect pin. Then have a software Schmidt Trigger verify the logic level at the begin-
ning and end of the coordinate-measurement sequence. Install a Pen IRQ handler function that
changes the measurement mode to software triggered and disables Pen IRQ interrupts. Then install
a timer handler that software-triggers a sequence when the timer expires and then stops the timer.
Next, install an end-of-sequence interrupt handler that reads the measurement results and deter-
mines whether the pen is still down. If the pen is down, the handler starts the timer for triggering the
next measurement. The handler discards the first set of measurements taken during the initial Pen
Down detection. Otherwise, the handler posts the current pen position to some sort of OS queue.
Enable Pen Triggered Measurements to start the system.
Table 23-16. GS Register
BIT
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
FIELD
///
RESET
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RW
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
BIT
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FIELD
///
BRONOUT
PENIRQ
CBSTATE
CBTAG
RESET
0
0
0
0
0
0
—
0
0
0
0
1
0
0
0
0
RW
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
ADDR
0xFF 0x18
Table 23-17. GS Register Definitions
BIT
NAME
DESCRIPTION
31:10 ///
Reserved
Read as zero.
9 BROWNOUT
Brown-Out Raw Interrupt Status
0 = Brown-out Interrupt is not active.
1 = Brown-out Interrupt is active.
This bit is undefined at reset.
8 PENIRQ
Pen IRQ Raw Interrupt Status*
0 = Pen IRQ Interrupt is not active.
1 = Pen IRQ Interrupt is active.
7:4 CBSTATE
Control Bank State Machine Status
0001 = Waiting for sequence start trigger.
0010, 0100, 1000 = Conversion sequence is in progress.
3:0 CBTAG
Current Conversion Tag Number
Specifies the current conver-
sion tag number.