@peewee32 hooray, will try firmware. But first I must assemble camera back. Because one small drop equals big lens scratch 
https://photos.google.com/share/AF1QipPwc8nvlVznPvDUJiBpO-_OdEKMNldybXHg_ez-d-1QFwy4M3sNvUDfE5PL4s96ZQ/photo/AF1QipPWlxP7vwYrCH49r8IHYF4T-yBsrAi2WNMeBI6x?key=MGVwS3hpMHpwUDduZzVMSnFHMHdFQWEwX0phX1ZB
Waiting for second camera 
If you communicate with Harry Wang, please could you ask if its possible to add subsecond time to exif?
With full second time in EXIF and connection with external GPX, gaps between images are not equal.
Some details about my external trigger.
Switched from sandisk extreme to Samsung evo card. Don’t know why, but write tests on sandisk card showed after while “down peaks” of write speed. (under 7M/s) Samsung write speed was line (more or less).
And after tweaking waiting time of PIC closer to 2 seconds, it works OK.
Mapillary last sequence with first camera with ISO 50, shutter auto.