Tflite classification memory error

im trying to do some letter detection on the openmv cam H7
im trying to train my own model with edge impulse duo to the fact that i only need to detect 3 letters
im using mobile net 2,when im trying to do some classification with my camera but when the program reaches the classification line the program stops and the flowing error occurs:
MemoryError: Out of fast Frame Buffer Stack Memory! Please reduce the resolution of the image you are running this algorithm on to bypass this issue!
the network works with 120 * 120 pictures
can you help me with this error?

Shrink the model input size to 48x48 pixels.

ive done that but the error still occurs!
ive came to understand that the mobile net networks end up much bigger than normal CNNs
the mobilenet network is about 700kb while the normal CNNs end up being around 40 50kb and changing the input image size does make a difference but apparently its not enough
what is the maximum size of a neural net that can function on a openmv cam h7?
i also need to do some contour detection besides running the model does that make any change to the limits of the models size?

The H7 regular can hold a model that’s about 200kb. Edge impulses default image classifier with a 48x48 input network should work.

OK, thanks for your quick and helpful response