MAX11800_10 Datasheet, PDF (24/57 Pages) Maxim Integrated Products – Low-Power, Ultra-Small Resistive Touch-Screen Controllers with I2C/SPI Interface

Low-Power, Ultra-Small Resistive Touch-Screen
Controllers with I²C/SPI Interface
Panel Setup, Measurement, and Scan Commands
To simplify measurement procedures, the MAX11800–
MAX11803 support three types of commands: panel
setup commands (PSU), panel measurement commands
(PMC), and combined measurement commands (CMC).
In direct conversion mode, the MAX11800–MAX11803
can use all three types of commands. Using individual
panel setup and measurement commands allow for a
high degree of customization based on decisions made
by the AP, while using combined commands signifi-
cantly simplifies the complete measurement process
and reduces communications between the AP and the
MAX11800–MAX11803.
In autonomous mode, the MAX11800–MAX11803 use
combined commands to control and automate all
aspects of panel setup, measurements, and timing. See
the Operating Mode Configuration Register (0x0B) sec-
tion for more details.
Direct Conversion Mode Operations
In direct conversion mode, the AP requests individual
panel setup and conversion operations or automated
combinations of measurements (X and Y, X and Y and
Z1, or X and Y and Z1 and Z2 combined). Unlike
autonomous conversion modes, the AP maintains control
over the initiation of panel setup, measurements events,
and the sampling frequency. Figure 8 shows the state
machine transitions for direct conversion mode.
Interrupt Modes
The MAX11800–MAX11803 support two direct conver-
sion interrupt modes. The two direct conversion modes
are the continuous interrupt mode (CINT) and the edge
interrupt mode (EINT).
Continuous Interrupt Mode
In continuous interrupt mode, the panel returns to TDM
and idle. The current status of the panel is then sent
through TIRQ. The continuous interrupt mode is the
least efficient mode in current consumption for long
duration of touches. The power consumption is approxi-
mated by P_TOUCH = V_DD²/R_PU. The power consump-
tion levels observed when the panel is not touched is
limited by the junction leakage currents of the
MAX11800–MAX11803.
NO
COMMAND
SETUP
X
PANEL
NO
COMMAND
SETUP
Y
PANEL
NO
COMMAND
SETUP
Z
PANEL
TOUCH
DETECT
TIME IS UP
X
DONE AND
DETECT ^CONTINUOUS
Y
ACQUIRE
Z1
ACQUIRE
Z2
ACQUIRE
AUX
DONE AND
ACQUIRE ^CONTINUOUS
AVERAGE
CONVERSION
LAST
CONVERSION
AVERAGE
CONVERSION
LAST
CONVERSION
USER COMMAND
INTERNAL TRANSITION
Figure 8. State Machine Transitions (Direct Conversion Mode)
TOUCH-
DETECT
FINE
PULLUP
TIME IS UP
TOUCH-
DETECT
FINE
PULLUP
24 ______________________________________________________________________________________