Arducam RevC + OV2640 module + Ardu Mega2560 R3 + BLE shield

[Billy Taylor]

Hi, have you heard of any success in stacking the ArduCam with a BLE shield? Both the ArduCam and BLE shield work well separately with the Arduino, but the ArduCam SPI bus check fails if they are stacked together. I wonder if there are SPI CS (or I2C slave address?) conflicts that are responsible, and if so, how I might change the CS pin (or I2C slave address?) for the BLE shield?

Thanks
Billy

[Alex-w]

hi Billy:
1.I haven't done this yet。BLE'S SPI com is not a standard SPI 。It does not have CS pin。Strictly speaking，BLE Shield communicates with Arduino through the ACI (Application Controller Interface)。ACI is similar to SPI but does not actually work as SPI. SPI is consist of MOSI, MISO, SCK and SS, whereas ACI is consist of MOSI, MISO, SCK, REQN and RDYN.

[Billy Taylor]

Thanks Sean.

Is it possible to use other pins for RDYN and REQN, perhaps by uploading modified firmware to the BLE shield or other means?

[Alex-w]

No， I have not tried。
In ACI,data exchanged still through MOSI and MISO, and SCK provides the clock generated by master.
When master wants to request data from BLE Shield, it puts the REQN to low until RDYN line is put to low by BLE Shield, and then master generates the clock to read out the data. After reading out the data, master will release the REQN and BLE Shield release the RDYN, put them to high.
If BLE Shield has data to transmit to master, it will put the RDYN to low to indicate master, even though master havn't requested data and REQN is idle. If master detectes a low level condition on RDYN, it will put REQN to low and generate the clock to read out the data.After reading out the data, both REQN and RDYN will be put to high.Note that REQN is controlled by master while RDYN is controlled by BLE Shield.