pca9685 NXP Semiconductors, pca9685 Datasheet - Page 27

• Manufacturer Part Number: pca9685
• Description: 16-channel, 12-bit Pwm Fm+ I 2c-bus Led Controller
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA9685_1
Product data sheet
7.6 Software reset
The Software Reset Call (SWRST Call) allows all the devices in the I
the power-up state value through a specific formatted I
correctly, it implies that the I
bus.
The SWRST Call function is defined as the following:
The I
a ‘SWRST Call Abort’. The PCA9685 does not initiate a reset of its registers. This
happens only when the format of the SWRST Call sequence is not correct.
1. A START command is sent by the I
2. The reserved SWRST I
3. The PCA9685 device(s) acknowledge(s) after seeing the General Call address
4. Once the General Call address has been sent and acknowledged, the master sends
5. Once the correct byte (SWRST data byte 1) has been sent and correctly
Fig 12. SWRST Call
sent by the I
‘0000 0000’ (00h) only. If the R/W bit is set to ‘1’ (read), no acknowledge is returned to
the I
1 byte with 1 specific value (SWRST data byte 1):
a. Byte 1 = 06h: the PCA9685 acknowledges this value only. If byte 1 is not equal to
If more than 1 byte of data is sent, the PCA9685 does not acknowledge any more.
acknowledged, the master sends a STOP command to end the SWRST Call: the
PCA9685 then resets to the default value (power-up value) and is ready to be
addressed again within the specified bus free time (t
2
C-bus master must interpret a non-acknowledge from the PCA9685 (at any time) as
06h, the PCA9685 does not acknowledge it.
2
C-bus master.
2
S
START condition
C-bus master.
0
0
General Call address
Rev. 01 — 24 July 2008
0
2
2
C-bus address ‘0000 000’ with the R/W bit set to ‘0’ (write) is
0
C-bus is functional and that there is no device hanging the
0
16-channel, 12-bit PWM Fm+ I
0
0
2
C-bus master.
0
A
from slave
acknowledge
0
0
SWRST data byte 1
0
2
0
C-bus command. To be performed
BUF
0
).
1
acknowledge
from slave
1
2
0
condition
002aac900
C-bus LED controller
2
STOP
A
C-bus to be reset to
PCA9685
© NXP B.V. 2008. All rights reserved.
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