Table 2-16. Gs Register; Table 2-17. Gs Fields; General Status Register (Gs) - Sharp LH79524 User Manual

LH79524/LH79525 User's Guide

2.2.2.7 General Status Register (GS)

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, the PENIRQ bit is
31 30 29 28
0 0 0 0
RO RO RO RO RO
15 14 13 12
///
0 0 0 0
RO RO RO RO RO
NAME
/// Reserved Reading returns 0. Write the reset value.
Brown-Out Raw Interrupt Status
BROWNOUT
1 = Brown-out Interrupt is active.
0 = Brown-out Interrupt is not active.
Pen IRQ Raw Interrupt Status
PENIRQ*
1 = Pen IRQ Interrupt is active.
0 = Pen IRQ Interrupt is not active.
Control Bank State Machine Status The only valid values are:
0001 = Idle state; waiting for sequence start trigger
CBSTATE
0010 = GET_DATA state
0100 = WAIT_CONV state
1000 = END_OF_SEQ state
Current Conversion Tag Number Contains the current conversion tag
CBTAG
number.
only set during the one A2DCLK period of the GET_DATA state. To determine if the pen has been
down at all, examine the IS:PENSYNC_UM bit. To determine if the pen was down at both the start
and the end of a measurement sequence, use analog measurements of the pen IRQ voltage at the
beginning and the end of the sequence. Then have a software Schmidt Trigger verify the logic level
at the beginning and end of the coordinate-measurement sequence. Install a Pen IRQ handler func-
tion that changes the measurement mode to software triggered and disables Pen IRQ interrupts.
Then stop the timer when it expires. Next, install an end-of-sequence interrupt handler that reads the
measurement results and determines 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 measure-
ments taken during the initial Pen Down detection. Otherwise, the handler posts the current pen posi-
tion to some sort of OS queue. Enable Pen Triggered Measurements to start the system.
Analog-to-Digital Converter/Brownout Detector

Table 2-16. GS Register

27 26 25 24 23
///
0 0 0 0 0
RO RO RO RO
11 10 9 8 7
0 0 1 0 0
RO RO RO RO
0xFFFC3000 + 0x18

Table 2-17. GS Fields

DESCRIPTION
Version 1.0
22 21 20 19 18
0 0 0 0 0
RO RO RO RO RO
6 5 4 3 2
CBSTATE CBTAG
0 0 1 0 0
RO RO RO RO RO
17 16
0 0
RO RO
1 0
0 0
RO RO
2-19