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Please take a look at this comment: openmv/openmv#2970 (comment) |
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kwagyeman
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Feb 16, 2026
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| # Prime DMA system before reading raw events. | ||
| # Prime on first size or poll request. | ||
| primed = False | ||
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| # Only grab next frame when current FIFO buffer has been fully streamed. | ||
| frame_available = False | ||
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| class EventChannel: | ||
| def size(self): | ||
| global primed | ||
| if not primed: | ||
| primed = True | ||
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| return event_length | ||
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| def shape(self): | ||
| return (event_length, 1) | ||
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| def read(self, offset, size): | ||
| global frame_available | ||
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| if frame_available: | ||
| end = offset + size | ||
| mv = events_mv[offset:end] | ||
| if end == event_length: | ||
| frame_available = False | ||
| return mv | ||
| return bytes(size) | ||
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| def poll(self): | ||
| global primed | ||
| if not primed: | ||
| primed = True | ||
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| return frame_available | ||
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| protocol.register(name='events', backend=EventChannel()) | ||
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| while True: | ||
| if not frame_available and primed: | ||
| csi0.ioctl(csi.IOCTL_GENX320_READ_EVENTS_RAW) | ||
| frame_available = True No newline at end of file |
Member
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Suggested change
| # Prime DMA system before reading raw events. | |
| # Prime on first size or poll request. | |
| primed = False | |
| # Only grab next frame when current FIFO buffer has been fully streamed. | |
| frame_available = False | |
| class EventChannel: | |
| def size(self): | |
| global primed | |
| if not primed: | |
| primed = True | |
| return event_length | |
| def shape(self): | |
| return (event_length, 1) | |
| def read(self, offset, size): | |
| global frame_available | |
| if frame_available: | |
| end = offset + size | |
| mv = events_mv[offset:end] | |
| if end == event_length: | |
| frame_available = False | |
| return mv | |
| return bytes(size) | |
| def poll(self): | |
| global primed | |
| if not primed: | |
| primed = True | |
| return frame_available | |
| protocol.register(name='events', backend=EventChannel()) | |
| while True: | |
| if not frame_available and primed: | |
| csi0.ioctl(csi.IOCTL_GENX320_READ_EVENTS_RAW) | |
| frame_available = True | |
| # Only grab next frame when current FIFO buffer has been fully streamed. | |
| frame_available = True | |
| class EventChannel: | |
| def size(self): | |
| return len(events_mv) | |
| def shape(self): | |
| return (len(events_mv), 1) | |
| def read(self, offset, size): | |
| global frame_available | |
| if frame_available: | |
| end = offset + size | |
| mv = events_mv[offset:end] | |
| if end == len(events_mv): | |
| frame_available = False | |
| return mv | |
| return bytes(size) | |
| def poll(self): | |
| return frame_available | |
| protocol.register(name='events', backend=EventChannel()) | |
| while True: | |
| if not frame_available: | |
| events = csi0.ioctl(csi.IOCTL_GENX320_READ_EVENTS_RAW) | |
| events_mv = memoryview(events.bytearray()) | |
| frame_available = True |
Member
There was a problem hiding this comment.
Since you have the fifo enabled, you have to treat each events object returned as a new image which you have to get the byte array to.
What's happening above is that the frames accumulate in the fifo onboard. When a USB access happens it's going to suck out whatever the latest frame is, unlock the main loop to pop another off the head of the fifo, and then lock it again for USB to suck out another frame.
As long as the rate at which frames are removed from the fifo is faster than the fifo filling up, then you shouldn't drop any data.
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Adds MicroPython scripts for streaming raw 32-bit words from the GENX320 to the user's PC.