AN2827 Datasheet, PDF (27/30 Pages) STMicroelectronics – Driver for double flash LED with I²C interface

AN2827
Examples of register setup for each mode
8.5
Example 5: flash pulse longer than 1.5 s
Suppose the targeted value of the flash current is 240 mA. The task is to make a single flash
pulse with a 4-second duration.
FTIM must be reloaded into the COMMAND REGISTER before the internal flash timer
reaches zero. This guarantees that the flash will continue and not stop after 1.5 seconds.
The first packet must also contain the DIMMING REGISTER data if this data is different from
that which was used in the previous operation.
Packet 1
Sets flash mode with a 1.5 s duration and the proper dimming.
Table 26. I²C data packet for activating flash mode
Byte Hex
Binary
1
62 0 1 1 0 0 0 1 0
2
00 0 0 0 0 0 0 0 0
3
DF 1 1 0 1 1 1 1 1
4
05 0 0 0 0 0 1 0 1
Comment
Device address + R/W bit
Command register address
Data of the command register
Data of the dimming register
Packet 2
Sets flash mode with a 1.5 s duration. Dimming data is not reset since it is the same as for
Packet 1.
Table 27. 2^nd I²C data packet for restart of flash mode
Byte Hex
Binary
1
62 0 1 1 0 0 0 1 0
2
00 0 0 0 0 0 0 0 0
3
DF 1 1 0 1 1 1 1 1
Comment
Device address + R/W bit
Command register address
Data of the command register
Packet 3
Sets flash mode with a 1.5 s duration. Dimming remains the same.
Table 28. 3^rd I²C data packet for restart of flash mode
Byte Hex
Binary
Comment
1
62 0 1 1 0 0 0 1 0
2
00 0 0 0 0 0 0 0 0
3
DF 1 1 0 1 1 1 1 1
Device address + R/W bit
Command register address
Data of the command register
Packet 4
Sets flash mode with a 1 s duration. Dimming remains the same.
Doc ID 15047 Rev 1
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