Application Notes

ArduCAM Camera Shield Software Application Note
www.ArduCAM.com
9
CMD 0x00 0x00 0x00 0x00 0x00 0x00 0x00
SCLK
MOSI
CSn
MISO
Command Phase
Data Phase
dummy
D0 D1 D2 Dn-2 Dn-1 Dn
CMD 0x00 0x00 0x00 0x00 0x00 0x00 0x00
Command Phase
Data Phase
Dn+1
Dn+2 Dn+3 Dn+4 Dm-2 Dm-1 Dm
First read transaction
following read transaction
Figure 5 Burst read timing diagram 1
For hardware platforms (ArduCAM-Shield-V2, ArduCAM-Mini-5MP-Plus), you don't need
to worry about the first byte. Detail timing can be found from Figure 6.
CMD 0x00 0x00 0x00 0x00 0x00 0x00 0x00
SCLK
MOSI
CSn
MISO
Command Phase
Data Phase
D0 D1 D2
Dn-2 Dn-1 Dn
CMD 0x00 0x00 0x00 0x00 0x00 0x00 0x00
Command Phase
Data Phase
Dn+1
Dn+2 Dn+3 Dn+4 Dm-2 Dm-1 Dm
First read transaction
following read transaction
D3
Figure 6 Burst read timing diagram 2
5.6 Rewind Read Operation
Rewind read is useful for some application that need access the same pixel data multiple
times. By sending the command code 0x84 and write ‘1’ to bit[5] in the data phase, it will reset the
memory read pointer to ZERO. Then user can read the image data from the start of the memory.
5.7 Low Power Mode
For some battery powered device power consumption is very important. There are two levels
to achieve low power mode, user have to combine these modes according to their own power
strategy.
5.7.1 Power down the sensor circuit
It is achieved by controlling the power enable pin of the onboard LDOs. The power enable
pin is controlled by the GPIO[2] of ArduChip. By sending the command code 0x86 and write ‘1’
to bit[2] to enable the LDOs, or write ‘0’ to bit[2] to disable the LDOs to save power. Note that
power down the sensor circuit, the camera settings are lost. User should reinitialize the sensor
when power up the sensor circuit again.
5.7.2 Sensor standby
It is achieved by controlling the power enable pin of the onboard LDOs. The power enable
pin is controlled by the GPIO[1] of ArduChip. By sending the command code 0x86 and write ‘1’
to bit[1] to set the sensor into standby mode, or write ‘0’ to bit[1] to set the sensor out of standby
mode. Note that the sensor settings are not lost when in standby mode, and reinitialize is not
needed.
6 ArduCAM APIs
There are a set of API functions that issue different commands to ArduCAM shield.
6.1 void InitCAM (void)
InitCAM function initializes the hardware information of the user system, such as the SPI
chip select port initialization and image sensor slave address initialization.