Altitude Hold version of Silverware can be found in AH branch of Silverware.

On the left, the barometer Bwhoop B-03 can be recognized by the pressure filter foam pad. On the right is the BWHOOP B-03 Pro, without barometer.

On linux, a branch can be checked out like this:

$ git clone https://github.com/silver13/BoldClash-BWHOOP-B-03.git
Cloning into 'BoldClash-BWHOOP-B-03'...
remote: Counting objects: 1130, done.
remote: Compressing objects: 100% (50/50), done.
remote: Total 1130 (delta 72), reused 90 (delta 64), pack-reused 1016
Receiving objects: 100% (1130/1130), 1016.66 KiB | 2.01 MiB/s, done.
Resolving deltas: 100% (717/717), done.
$ cd BoldClash-BWHOOP-B-03/
$ git checkout AH
Branch AH set up to track remote branch AH from origin.
Switched to a new branch 'AH'
$ git status
On branch AH
Your branch is up-to-date with 'origin/AH'.
$

Added configuration (config.h) options:

// Springloaded centre is zero throttle
#define USE_STOCK_SPRINGLOADED_TX

// Hold throttle on centered stick
// #define USE_STOCK_SPRINGLOADED_HOLD

// Use BARO sensor - type in hardware.h
#define ENABLE_BARO

USE_STOCK_SPRINGLOADED_TX is used to make use of normal bwhoop springloaded TX. The throttle is centered with springs and this define makes the center position 0% throttle. Pushing down decreases alt (when in BARO or SPRINGLOADED_HOLD mode).

USE_STOCK_SPRINGLOADED_HOLD is a poor man's altitude hold. This makes center throttle 0% throttle adjust, and adds or decreases throttle when pushing or pulling throttle (using a ^5 exponential curve for easier adjustments around centre). Center will keep the last throttle, so when carefully adjusted this will keep the drone in place. Be careful, I tend to overshoot quite a lot while trying this mode.

ENABLE_BARO Enables barometer supported Altitude Hold. This is best used in combination with USE_STOCK_SPRINGLOADED_TX. In ENABLE_BARO mode the drone starts off when armed, throttle up will quickly ascend the drone to ~50cm. Holding down the throttle (< 85%) for more than one second switches off motors.