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Analog-to-Digital Converter/Brownout Detector
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.
BIT
FIELD
RESET
RW
BIT
FIELD
RESET
RW
ADDR
BIT
31:10
9
8
7:4
3:0
NOTE: *If the Idle state is configured to bias a 4-wire Touch Screen for Pen IRQ detect, and if the pen is held
23-18
31
30
29
28
0
0
0
0
R
R
R
R
15
14
13
12
///
0
0
0
0
R
R
R
R
Table 23-17. GS Register Definitions
NAME
///
Reserved Read as zero.
Brown-Out Raw Interrupt Status
0 = Brown-out Interrupt is not active.
BROWNOUT
1 = Brown-out Interrupt is active.
This bit is undefined at reset.
Pen IRQ Raw Interrupt Status*
PENIRQ
0 = Pen IRQ Interrupt is not active.
1 = Pen IRQ Interrupt is active.
Control Bank State Machine Status
CBSTATE
0001 = Waiting for sequence start trigger.
0010, 0100, 1000 = Conversion sequence is in progress.
Current Conversion Tag Number Specifies the current conver-
CBTAG
sion tag number.
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.
LH75400/01/10/11 (Preliminary) User's Guide
Table 23-16. GS Register
27
26
25
24
23
///
0
0
0
0
0
R
R
R
R
R
11
10
9
8
7
0
0
—
0
0
R
R
R
R
R
0xFFFC3000 + 0x18
DESCRIPTION
6/25/03
22
21
20
19
18
0
0
0
0
0
R
R
R
R
R
6
5
4
3
2
CBSTATE
CBTAG
0
0
1
0
0
R
R
R
R
R
17
16
0
0
R
R
1
0
0
0
R
R
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