Wiring OV7670 Camera to T4.0 and stream images

[JoeJohnson34]

Hello, I am working on correctly wiring an OV7670 without FIFO RAM camera sensor to a teensy 4.0. My goal is to stream the images via USB to my computer (similar to this example). I haven't found a wiring diagram specifically for teensy 4.0. Below is how I think it should be done but I would appreciate guidance on this as I don't want to fry any components.

For reference, the labeled pin layout of the sensor is in the following picture with the exception that PWDN is labeled "PWNN" on my sensor:

I will power the sensor by an external power source rather than pulling power from teensy. Below is a table of the sensor pins and which pins I believe they should connect to on teensy 4.0 (OV7670 > T4).

3.3V > 3.3V power source
GND  > Common ground
SCL  > 19 (with 3.3V power and 10k resistor)
SDA  > 18 (with 3.3V power and 10k resistor)
VS   > 17
HS   > 16
PCLK > 12
MCLK > 23 (with voltage divider)
D7   > 7
D6   > 6
D5   > 5
D4   > 4
D3   > 3
D2   > 2
D1   > 1
D0   > 0
RST  > 3.3V
PWNN > Common ground

Finally, I believe that I need to add a couple resistors. I was having trouble finding documentation on this and did see a few conflicting resources. However, for the following I used the previously linked to example starting at the 4:42 mark of the video.

SCL - Has a 10k resistor from 3.3V power source to SLC on sensor and then a wire to pin 19 on teensy. (mark 5:33)
SDA - Same as SCL with a 10k resistor from 3.3V power source to SDA on sensor and then a wire to pin 18 on teensy. (mark 5:33)
MCLK - A voltage divider is necessary. There is a wire from common ground to a 1k resistor and a 680 Ohm resistor to pin 23 on Teensy. Between the resistors, I wire to MCLK on the sensor. (mark 4:43)

Please let me know if I have anything wrong with this set up. Thank you for reading my post!

 

[KurtE]

Not sure if there is anything wrong or not with your setup. Several of us played with these a year or two ago and there is some interesting information on them in a few different threads.

like:
https://forum.pjrc.com/threads/63195-Problem-trying-to-read-OV7670-camera-under-IRQ-Teensy-4-0
https://forum.pjrc.com/threads/61537-SPI-TFT-OV7670-camera-project-on-teensy-4

Now if you had a T4.1 I would suggest looking at:
https://forum.pjrc.com/threads/64132-CSI-Camera-Library
As the T4.1 has enough pins to use the CSI sub-system of the IMXRT processor.

If you were using the MicroMod Teensy I would suggest looking at the stuff, we were playing with using FlexIO to read the camera.
Most of the stuff was in the Beta testing thread:
https://forum.pjrc.com/threads/66771-MicroMod-Beta-Testing

But on T4, the best stuff we were doing, was to use DMA to read in the pixel data, which implies you want all of the D0-7 to be on the same Teensy IO port.
Back then I was playing with the library: https://github.com/KurtE/Arduino_OV767X/tree/teensy_micromod

For the 4.1 doing DMA stuff I was using the pins:

#else
// For T4.1 can choose same or could choose a contiguous set of pins only one shift required.
// Like:  Note was going to try GPI pins 1.24-21 but save SPI1 pins 26,27 as no ...
#define OV7670_PLK   4
#define OV7670_XCLK  5
#define OV7670_HREF  40 // AD_B1_04 1.20 T4.1...
#define OV7670_VSYNC 41 // AD_B1_05 1.21 T4.1...

#define OV7670_D0    17 // AD_B1_06 1.22
#define OV7670_D1    16 // AD_B1_07 1.23
#define OV7670_D2    22 // AD_B1_08 1.24
#define OV7670_D3    23 // AD_B1_09 1.25
#define OV7670_D4    20 // AD_B1_10 1.26
#define OV7670_D5    21 // AD_B1_11 1.27
#define OV7670_D6    38 // AD_B1_12 1.28
#define OV7670_D7    39 // AD_B1_13 1.29
#endif
//      #define OV7670_D6    26 // AD_B1_14 1.30
//      #define OV7670_D7    27 // AD_B1_15 1.31


#endif

The T4 may not have 8 contiguous ones, so the DMA after processing is slightly more complex. Some of the threads show what some of us were using.

 

[JoeJohnson34]

Hi KurtE. Thank you for the links. These are full of great info! I'm still struggling with the wiring of the camera to the T4.0. Any chance there is a diagram floating around somewhere that I haven't been able to uncover? This would be very helpful. Thanks.