Texas Instruments LP8580EVM, Руководство пользователя

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Examples
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18 SNVU495 – March 2016
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Copyright © 2016, Texas Instruments Incorporated
LP8580 Evaluation Board
1. Turn on the Dimming PWM generator by checking the Enable checkbox. Set the frequency to 0.1 kHZ
and the duty cycle to 20%, then click the update button.
2. Write 0x0504 to the BL_MODE register under the Configuration memory block. This sets the
brightness control to PWM input.
3. The brightness of the whole backlight can now be controlled by changing the duty cycle in the dimming
control. The brightness of the individual LED strings can still be controlled with LEDx_B0 registers.
Figure 16. PWM Settings
6.4 Turning ON the VCOMTRIM Output
To turn on the VCOMTRIM current source, follow the next steps. Note that an external voltage source
must be connected to the NAVDD and AVDD pins of the LP8580EVM. The LP8580 supports both unipolar
and bipolar voltages. More information on the VCOMTRIM can be found in the LP8580 data sheet.
1. Write 0x0001 into the VCOM_CONFIG register under the Configuration memory block. This enables
the VCOMTRIM output.
2. VCOMTRIM output current can be controlled with the VCOM_TRIM_ADJ0 register under the
VCOM_DYNAMIC_TRIM register block. Set desired output current to the VCOM_TRIM_ADJ0 register.
3. The new VCOM_TRIM_ADJ0 value must be latched to the VCOMTRIM current output before it takes
effect. This is done by writing 0x0001 to the VCOM_DB_CONTROL register under the
VCOM_DYNAMIC_TRIM register block.
6.5 Saving the EEPROM Content to a Text File
EEPROM content can be saved to a text file for future use.
1. Read EEPROM values into the EEPROM content window by clicking the Read button under the
EEPROM content window. It is not necessary to unlock EEPROM to read the values.
2. Click the Save button, give the text a file name, and click Save . This saves the EEPROM settings to a
text file.
The text file can be opened with any text editor and modified as needed. Each row in the text file has a
register address followed by the register data in a hexadecimal format.
6.6 EEPROM Reprogramming
EEPROM content can be reprogrammed easily from a text file containing the new EEPROM values. To
reprogram the EERPOM, follow the steps below:
1. Start up the device as described in Section 6.1 .
2. Unlock the EEPROM by clicking the Unlock button on the EEPROM Control area.
3. Verify that EEPROM was unlocked successfully by clicking the Read status button. The EEPROM
unlocked indicator should turn red indicating that EEPROM is unlocked.
4. Click the Load button and browse to the location where the EEPROM text file is located. Select the
text file and click Open . New values are loaded to the EEPROM content window; however, the new
values are not written into the EEPROM of the LP8580 IC.
5. To write the new values into the EEPROM, click the Write button. This writes the EEPROM values in
the EEPROM content window to the LP8580 EEPROM.
6. To read the newly programmed values from the LP8580 EEPROM to the control registers, click the