Blackbox rate and flash

Betaflight stores the rate as a power of two. 1/1 logs every PID loop. 1/2 logs every second loop. 1/4, 1/8 and 1/16 follow. The label adds the resulting speed when the board has reported a loop time, so an 8 kHz loop shows 1/2 as 4 kHz and 1/4 as 2 kHz. A 4 kHz loop shows 1/2 as 2 kHz. Read the number on your board.

The footer says higher rates show more detail for tuning but fill the flash faster, and that 1/2 on an 8 kHz loop is a good start for filter tuning. Drop toward 1/8 or 1/16 when the chip fills before the flight ends. Go toward 1/1 only when you need the detail and the flash has room.

INAV uses a numerator and a denominator. The list is 1/1, 1/2, 1/4, 1/8, 1/16 and 1/32. A saved rate that is not one of those still shows as that fraction. The same rule applies: a larger fraction fills the storage sooner, and the choice is refused while armed.

The Logging tab is a different recorder. That one writes a CSV on the phone or computer, limited by Bluetooth or USB. Blackbox is the high-rate file on the craft. Use this rate for a flight you will open in the log viewer.

Onboard flash shows a ring of how full it is, the bytes used, and the bytes free. At zero it says empty, ready to record. Above 90 percent it warns that the chip is almost full and asks you to download and erase soon. While the chip is erasing, the ring says so, and a large chip can take up to two minutes.

Download and Erase are off while armed, while a transfer is already running, while the chip is erasing, and while the flash is empty. Disarm to download or erase logs. Erase asks you to confirm, because everything on the onboard flash is deleted. Download first if you still need the flight.

An SD card is not downloaded over the flight controller link. On a computer or Android you can open the card as a USB drive, or use a card reader. iPhone has no USB host, so the card is read with a card reader. A serial logger such as OpenLager is the same idea: the file is on that logger's card, not in a download button.

Betaflight can also pick None. Armed with None does not show Recording. Armed with flash, an SD card, or a serial logger does. INAV has no None. Its devices are serial, onboard flash and SD card, and it shows Recording whenever the craft is armed.

On Betaflight, when the firmware sends a field mask, a second card lists the groups. On records that group. Off leaves it out so the flash lasts longer. A new board logs everything. The groups are PID, RC commands, setpoint, battery, magnetometer, altitude, RSSI, gyro, accelerometer, debug, motor, GPS, RPM and unfiltered gyro.

A set bit in the mask is the group left out. Turning a switch off sets that bit. Turning it on clears the bit. The switches lock while armed, with the rate and the device.

A firmware built without blackbox logging shows that one sentence and no device, no rate and no fields. There is nothing to download until a build that includes blackbox is on the board.

Saved files on this device open in the log viewer. The tab accepts .BBL, .BFL and .TXT from Betaflight or INAV, lists up to 20 files, and deletes one with a swipe. The graphs are the viewer. This page is the rate and the storage.

Chrome or Edge connects over USB or Bluetooth. Android adds Wi-Fi. iPhone uses Bluetooth or Wi-Fi and has no USB host. Flash download uses the link you already have. The SD card still needs a card reader on iPhone.

The demo opens on onboard flash at 1/2, with every field included, and it can download a short simulated flight into the viewer. A real board replaces that with the chip and the flights on the craft. Disarm before you change the rate.