LM8500HVA9 National Semiconductor, LM8500HVA9 Datasheet - Page 16

• 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

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14.0 Calibration
in Table 3. Two Points Calibration, Table 4. Five Points
Calibration, and Table 5. Thirteen Points Calibration respec-
tively.
FIGURE 7. Thirteen Points Calibration Mapping
FIGURE 6. Five Points Calibration Mapping
FIGURE 5. Two Points Calibration Mapping
(Continued)
20037207
20037208
20037209
16
14.1 GENERAL CALIBRATION PROCEDURES
Calibration is invoked by sending a command byte of $BD
followed by a command byte to the device. The command
byte is broken into two parts: the high nibble states the
number of calibration points to performs and the lower nibble
states the active calibration point. For example, to do the first
calibration point for the two point calibration, the command
bytes of $BD and $11 are sent to the device. The device then
echos $BD and $11 back to the TS driver and waits for a
touch on the panel. When a touch is detected, the device
checks to see if the point is within the specified parameters
if the calibration point checking is enabled. If the calibration
point checking is disabled, the device will send a $C8 for OK
byte to the TS driver regardless of where the touch was
detected. This calibration point checking can be enabled or
disabled by sending a command byte of $A5 to the device.
When all the calibration points are done, the device will do a
self-test and send a command of $CB for OK or a command
of $CC for failed. If a $CC is received, the TS driver should
issue a warning stating the calibration was not done properly
and redo the calibration procedures. The flowchart for the
calibration procedures is shown in Figure 8.
Calibration point Theoretical X-value Theoretical Y-value
Calibration point Theoretical X-value Theoretical Y-value
Calibration point Theoretical X-value Theoretical Y-value
10
11
12
13
1
2
1
2
3
4
5
1
2
3
4
5
6
7
8
9
TABLE 5. Thirteen Points Calibration
TABLE 4. Five Points Calibration
TABLE 3. Two Points Calibration
127
895
127
895
127
511
895
127
895
127
511
895
895
511
127
511
623
623
319
319
127
895
127
895
895
127
127
895
895
127
895
127
319
623
623
319
511
511
511
511