NXP Semiconductors
UM11761
PCA9955BTW-ARD evaluation board
3. From Select COM Port list, select the correct COM (if more than one is available).
4. From Select Board list, select PCA9955B.
5. Click
Connect
. When the connection is established, all on-board LEDs are turned on.
6. From Device Setting list, Select
Disable
for the
OE
, and click
Set all
button. This will
disable the driver outputs (the LEDs turns off).
7. Select
Channels
tab. From here, select Brightness secondary tab. Set the duty cycle
for “CH2” – RGB1 blue, “CH4” – RGB2 green, and “CH6” – RGB red to 100%. Press
Write
button to set the individual selected values.
8. From the same tab, select
Output
secondary tab. Select for “CH0 Output Control”
the value
0x3=PWMx or GRPPWM
. Press
WriteAll
button to set the same value for
all channels.
9. Select
Gradation
secondary tab, select for Gradation Mode Select for CH0 Output
the gradation mode
0x1=Gradation
. Press
WriteAll
button to set the same value for
all channels.
10. Select
Groups
tab, and
Brightness
secondary tab. Set the “Group Duty Cycle” to
100%. Press
Write
button to set the selected value.
11. Select
Gain
secondary tab. Set for “Group 0” the Output Current Gain the value 255.
Press
Write
button to set the selected value.
12. Select
Hold
secondary tab. For “Hold ON/OFF Time Control for Group 0” set the
following values:
Enable
for
Hold On
and
Hold Off
, and any value which is different
from “0 s” for
Hold On Time
and
Hold Of Time
. Press
Write
button to set the
selected values.
13. Select
Gradation
secondary tab. For “GradationGroup0” set the following values:
Continuous
for
Operation
and
Start
for
Gradation
. Press
Write
button to set the
selected values.
14. Select
Define
secondary tab. For “Gradation Group Select for CH0 Output” select the
value
0x0=Group0
. Press
WriteAll
button to set the same value to all channels.
15. Go back to the
Settings
tab, select
Enable
for
OE
and click
Set all
button. The
selected group of LEDs will turn on and off, with the intensity according with the
previous settings.
16. Select again the
Groups
tab. Select
Gradation
secondary tab. For “Ramp Enable
and Rate Control for Group 0” select the following values:
Enable
for
Ramp Up
and
Ramp Down
, and any value but different from “0x00” for
Ramp Value
. Press
Write
button to set the selected values.
17. Select
Step time
secondary tab. For “Step Time Control for Group 0” select
8 ms
for
Cycle Time
. Press
Write
button to set the selected values.
Starting from these steps and using the datasheet, the user can combine different values
for the internal registers of the DUT, to understand, and test the functionality of the
PCA9955B LED driver.
9 Abbreviations
Acronym
Description
DUT
Device Under Test
ESD
Electro Static Discharge
EVK
Evaluation Board
GUI
Graphical User Interface
Table 10. Abbreviations
UM11761
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User manual
Rev. 1.0 — 18 March 2022
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