AN2827

Examples of register setup for each mode

Doc ID 15047 Rev 1

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8.3

Example 3: auxiliary LED running at 10 mA for 500 ms

The STCF05 must be in READY mode (both TRIG_EN and TCH_ON set to 0) to activate

the auxiliary LED.

A 10 mA output current will be reached when AUXI is set to 0x8.

AUXT must be set to 0x5 to obtain a 500 ms duration of the auxiliary LED lighting.

Writing the following three bytes to the STCF05 puts the device into READY mode. This can

be skipped if READY mode is already activated.

Writing the following three bytes to the STCF05 activates the auxiliary LED for the desired

time.

8.4

Example 4: red-eye reduction (multiple short flashes)

There are two ways of reducing red eye. The first one is to use hardware triggering of the

flashes through the TRIG pin. This is the most suitable and recommended solution, as it

reduces the usage of the I²C bus and the length of each flash pulse can be adjusted

continuously. The second solution is to use the software triggering feature, which means a

periodical reloading of the COMMAND register. This will however increase traffic on the I²C

bus and the flashes can only have a set length, adjustable in 100 ms steps only.

Table 19.

COMMAND register data for AUX_LED

CMD_REG

PWR_ON

TRIG_EN

TCH_ON

NTC_ON

FTIM_3

FTIM_2

FTIM_1

FTIM_0

1000

0000

MSB

LSB

Table 20.

AUX_LED register data

AUX_LED

AUXI_3

AUXI_2

AUXI_1

AUXI_0

AUXT_3

AUXT_2

AUXT_1

AUXT_0

1000

0101

MSB

LSB

Table 21.

I²C data packet for activating READY mode

Byte

Hex

Binary

Comment

1

62

01100010

Device address + R/W bit

2

00

00000000

Command register address

3

80

10000000

Data of the command register

Table 22.

I²C data packet for activating AUX_LED

Byte

Hex

Binary

Comment

1

62

01100010

Device address + R/W bit

2

02

00000010

Auxiliary LED register address

3

85

10000101

Data of the Auxiliary LED register