LM8500HVA9 National Semiconductor, LM8500HVA9 Datasheet - Page 17

• Manufacturer Part Number: LM8500HVA9
• Description: IC TOUCHSCREEN CONTROLLER 44PLCC
• Manufacturer: National Semiconductor
• Type: Resistiver

Specifications of LM8500HVA9

• Touch Panel Interface: 4-Wire
• Number Of Inputs/keys: 1 TSC
• Resolution (bits): 10 b
• Data Interface: UART
• Data Rate/sampling Rate (sps, Bps): 38.4k
• Voltage - Supply: 2.7 V ~ 5.5 V
• Current - Supply: 11.5mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 44-PLCC
• Voltage Supply Source: Single Supply
• For Use With: LM8500-REF-01 - BOARD EVALUATION LM8500
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Sampling Rate (per Second): -
• Other names: *LM8500HVA9

14.0 Calibration
14.2 CALIBRATION PROCEDURES WITH
COORDINATES CHECKING ENABLED
To do TS calibration with coordinates checking enabled, first
ensure the Calibration Coordinates Checking is enabled on
the device. This can be accomplished by sending a com-
mand byte of $B1 (Read Parameters command) and check-
ing the 5th bit of the 12th reply byte is set. Alternatively, if the
device is set to Calibration Coordinates Checking enabled
as default, this step can be skipped.
The TS driver sends the command byte to do calibration
($BD). The TS driver should wait for the reply bytes and
ensure it is the same command bytes it sent. The device
waits for a touch to be detected on the panel. Once a touch
is detected, the device checks it against the predetermined
FIGURE 8. Calibration Procedures with Coordinates Checking Enabled
(Continued)
17
calibration values as noted on Table 3. Two Points Calibra-
tion, Table 4. Five Points Calibration , and Table 5. Thirteen
Points Calibration. If the detected touch is within the pre-
defined value (
send a command of $C4 to the TS driver and store the
calibration point in the internal flash. The TS driver can now
send a command byte to do the next calibration point. If the
detected touch is not within the predefined value, the device
will send a reply byte of $C8 to the TS driver. Upon receiving
this reply byte, the TS driver can resend the calibration
command for the same calibration point, go the next calibra-
tion point, or abort the calibration process.
Once all the calibration points are done, the device does a
self-test. If the self-test was not successful, the device will
±
127 of the raw A/D value), the device will
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