Apple's Bongo Project Revolutionizing iPhone Buttons

TapTechNews July 10th news, the tech media AppleInsider released a blog post yesterday (July 9th) sharing photos of the prototype of Apple's iPhone 15Pro Max, with the biggest highlight being the adoption of the volume/power button buttons with the code name Bongo and a haptic design.

Apples Bongo Project Revolutionizing iPhone Buttons_0

Project Bongo Project Development History

TapTechNews reported on Apple's Project Bongo project in September 2023. Apple plans to redesign the volume and power buttons to bring new interactive experiences in terms of function and appearance.

In Apple's iPhone 4s launched in 2011, it started to use linear resonant actuators, greatly reducing the amount of noise generated and significantly improving the response time.

Apple then introduced the TapticEngine in the iPhone 6s launched in 2015, and users received haptic feedback by firmly pressing certain areas on the iPhone display.

The earliest design of the Bongo project can be traced back to 2021, that is, two years before the release of the iPhone 15Pro. The goal of this project is to replace the traditional mechanical buttons of the iPhone with improved haptic technology, and at the same time, Apple may hope to reduce the inherent hardware failure rate of mechanical buttons by adopting new technologies.

Project Bongo Project Profile

And Project Bongo is for the volume and power buttons, changing from traditional mechanical buttons to haptic buttons, detecting pressure and simulating the pressing of physical buttons by using the haptic engine (haptic feedback) that generates vibrations.

The feedback mechanism of pressing the haptic button of the Bongo project:

There is a flex sensor under the button, which can measure the pressure applied to the button.

The strain gauge detects the change in pressure and converts it into a change in resistance and accurately measures the change.

A signal is sent to the main logic board indicating that the button is pressed.

The main logic board issues a power supply instruction to the Bongo haptic engine

The Bongo haptic engine generates vibrations through the electromagnetic field

Then haptic feedback is generated through the vibration, and the slight upward movement towards the finger mimics the feeling of the physical button being pressed.

iPhone 15 Pro Max Prototype

The exposed one is the EVT stage prototype of the iPhone 15Pro Max. The device identification code during the development is D84, and the project code is Veyron.

Apple has cancelled the Bongo project in April 2023, and these EVT prototypes are the last batch of products that contain Apple's haptic buttons.

Apples Bongo Project Revolutionizing iPhone Buttons_1

The EVT prototype runs the InternalUI version of iOS 17. This means that the device contains a dedicated variant of the iPhone operating system for internal use by Apple engineers for development and testing purposes.

Apples Bongo Project Revolutionizing iPhone Buttons_2

Apple cancelled the haptic buttons of the iPhone 15Pro and iPhone 15Pro Max in the subsequent CRB and DVT prototype stages and instead used traditional mechanical buttons.


The source said that at the beginning of the design of the haptic buttons of Apple's iPhone 15Pro and iPhone 15Pro Max, it was a bit like a traditional mechanical button, and the user would still move after pressing. If the device is in the powered-on state, the haptic volume key and power key will generate feedback and a click sound after being pressed.

Apples Bongo Project Revolutionizing iPhone Buttons_3

The source said that after the user presses and releases the haptic button, the haptic feedback will be generated immediately, and its working principle is basically the same as that of Apple's MagicTrackpad, and there will be overall feedback and pressing sound.

If the device is in the powered-off state and the battery is depleted and cannot show the charging indicator light, after the user presses the haptic button, the button will still move, but no haptic feedback will be provided to the user. Simply put, this haptic experience requires power supply, and there is no haptic feedback without power supply.

Apples Bongo Project Revolutionizing iPhone Buttons_4

According to people familiar with the inside story, the Bongo-type button uses a dedicated firmware, which mentions the deep sleep mode. Once the device is shut down or inactive for a long time, the deep sleep mode may be activated.

The source revealed that even if a gloved finger touches the button or is used in the pocket, the button will respond to the pressure. This shows that the button can detect pressure changes without direct skin contact.

Key Hardware Components of Apple's Bongo Project and Their Working Principles

This component has two strain gauges, one on each side of the button. The strain gauge detects the change in pressure and converts it into a change in resistance within the circuit. The change in resistance leads to a change in voltage, and the potential difference between the two strain gauges is used to determine the location of the pressure origin (volume increase or volume decrease).

Apples Bongo Project Revolutionizing iPhone Buttons_5

To advance the Bongo project, Apple has developed the BongoHapticEngine, which is an electromagnetic-driven reluctance motor. Reluctance motors are an advanced motor commonly used in the field of microelectronics.

Apples Bongo Project Revolutionizing iPhone Buttons_6

By using reluctance motors, Apple can achieve a faster vibration speed than traditional vibration motors, while also providing a faster response time. The Bongo haptic engine is designed to provide more nuanced vibration feedback and a better user experience.

The Bongo haptic engine consists of a ferromagnetic core and a copper coil, which together form a solenoid. The haptic engine generates vibrations by oscillating relative to the attracting plate located directly below it.

Related Reading:

Exploring Apple's Bongo Project: The Haptic Volume/Power Buttons That Didn't Make It to the iPhone 15Pro Model