Interrupt Generation; Pen Adc (Padc) Operation; Table 15-2 Simplified Asp Signal Path Parameters - Motorola DragonBall MC9328MX1 Reference Manual

Parameter
R , R , R
p1 p2
C
d
R
pd
R
ref
QVDD
GND

15.3 Interrupt Generation

The following interrupts are provided:
• Pen Touch (pen down) Interrupt (IRQ number = 46)
It is generated upon a pen down event, can be programmed for level trigger or edge trigger.
• Pen Data Compare Interrupt (IRQ number = 9)
Every pen sample is compared with a desired value. If it is greater than (or less than, programmable)
the desired value, an interrupt will be generated.
• Pen-up Interrupt (IRQ number = 5)
In Auto XYU or ZXYU mode, with PUIE bit set, whenever a pen-up event is detected, an interrupt
signal is generated and sent to the interrupt controller.
• Pen FIFO Data Ready Interrupt (IRQ number = 33)
It is generated whenever there is at least 1 valid data in the FIFO.
• Pen FIFO Full Interrupt (IRQ number = 33)

15.4 Pen ADC (PADC) Operation

The Pen ADC, which has 9-bit accuracy, supports interfacing with a touch panel (X and Y-channel) and a
low voltage auxiliary input (U-channel). The sampling sequence as well as the sample rate is user
selectable and is up to 9.6 kHz for U-channel input, and 1.2 kHz for XYU + Auto Zero input.
There are 8 switches for the touch panel X and Y input signals, 2 switches for U-channel signal. In manual
mode, the switches are turned off/on per the input command from the Switch Control and Input Select
Logic block. In auto mode, they are controlled by a state machine, which is able to automatically generate
proper switch settings to select the target input signal for the PADC.
Sample data is stored into the Pen Sample FIFO, which is in 16-bit unsigned integer format. The FIFO is
circular buffer design, so if the data is not read fast enough, the FIFO will overflow and old data will be
overwritten. When an overflow occurs, the POV status bit is set in the Interrupt/Error Status Register.
MOTOROLA
Table 15-2. Simplified ASP Signal Path Parameters
Description
, R Pen ADC input resister
u1 u2
Noise decoupling cap
Pen-down detect resister
Analog reference resister
ASP power supply
ASP circuit ground
Analog Signal Processor (ASP)
Interrupt Generation
Typical Value
200 kOhm
0.01 uF
100 kOhm
40 kOhm
1.8 V
0 V
15-3