AR1100 Datasheet, PDF (31/58 Pages) Microchip Technology – AR1100 Resistive USB and RS-232 Touch Screen Controller

AR1100 RESISTIVE USB AND RS-232 TOUCH SCREEN CONTROLLER
• host presents last target (9^th in this example)
• operator touches (and releases) sensor at last tar-
get <0x55> <0x07> <0x00> <0x14> <0x08>
<0xXX> <0xXX> <0xYY> <0xYY>
• the 5^th byte indicates the calibration point 0x08
(the 9^th)
• 0xXXXX and 0xYYYY are RAW coordinates of the
touch point (16-bit, little endian)
• device indicates exit from calibration mode with
<0x55> <0x07> <0x00> <0x14> <0xFF>
<0xXX> <0xXX> <0xYY> <0xYY>
0xFF indicates ‘exit’ Calibration mode, XX and YY are
don’t care
• host terminates the target display
• device returns to normal operation
7.3 Sleep
The AR1100 supports a low-power, Sleep mode used
to conserve power when the device is not in use.
When in UART Communication mode, Sleep mode is
activated after a specified time interval (parameter reg-
ister: SleepDelay) during which no touch or communi-
cation took place. When in Sleep, the device can be
awakened by a touch or by any communication from
the host. The first byte of communication used to wake
up the device will be lost/ignored.
When in USB Communication mode, Sleep mode is
activated by a USB SUSPEND control transfer from the
host – the SleepDelay timer has no effect. Optionally, if
the host is configured to allow the device to awaken the
host (USB REMOTE WAKE-UP), the host will preface
the USB SUSPEND with a control transfer to enable
remote wake-up from the device. In this situation, a
touch can awaken the host; otherwise, only a RESUME
condition from the host will wake-up the AR1100.
7.4 Configure Sensor Type
The AR1100 must be configured for the sensor type
connected (i.e., 4W, 5W or 8W) using a combination of
the MODE input pin and configuration parameter
TouchOptions. For a 5W sensor, the mode input pin
must be grounded. For a 4W or 8W sensor, the mode
input pin should be open/disconnected. Additionally, bit
1 in Configuration register TouchOptions is used to
further select between 4W and 8W.
As seen in FIGURE B-1: “Schematic”, the MODE pin
is typically connected to a hardware jumper (J1).
Because this pin is equipped with an internal pull-up
resistor, it can be grounded with a jumper or simply left
disconnected (no jumper).
7.5 LED
The LED provides an indication of controller status. As
summarized in Table 7-1, a ‘fast’ blink indicates that a
touch is detected, and a ‘slow’ blink indicates no touch.
FIGURE 7-2:
LED SCHEMATIC
TABLE 7-1: LED INDICATOR
Behavior
Status
LED blinks slowly Controller is powered, awake
(once per second) and no touch is detected
LED blinks rapidly (5 Controller detects a touch
times per second)
LED is off
Controller has no power or is
asleep (suspended)
7.6 USB Mode Change
Low-level operations (configuration, calibration, boot
load) are supported in only 2 of the 4 communication
modes (i.e., UART and HID-GENERIC). If the AR1100
is operating in HID-MOUSE or HID-DIGITIZER mode,
it must be configured to HID-GENERIC for the low-level
operations, then reconfigured back to the desired
(default) device type.
Three 3-byte commands are provided to assign the
USB device type (refer to Section 5.0, Commands).
1. USB_MODE_GENERIC
2. USB_MODE_MOUSE
3. USB_MODE_DIGITIZER
Each command sets the default USB device type (in
nonvolatile memory), then resets the AR1100 – caus-
ing it to re-enumerate. All three device types will accept
the mode change commands as either a
SET_FEATURE control transfer or a standard WRITE
data transfer (via the interrupt-end point). The HID-
MOUSE device under MS Windows^® may be limited to
SET_FEATURE only.
 2011 Microchip Technology Inc.
DS41606B-page 31