nrf52833 vs nrf51822

AI Overview
The BBC micro:bit uses a
Nordic Semiconductor system-on-chip (SoC) as its main CPU, with the original version (V1) using the nRF51822 (ARM Cortex-M0) and the newer V2 featuring a more powerful nRF52833 (ARM Cortex-M4) for faster processing and Bluetooth 5.0. Both versions also have a separate NXP interface chip handling communication and other tasks.
Key CPU Details by Version:

micro:bit V1:
Processor: Nordic nRF51822
Core: 16 MHz ARM Cortex-M0
Memory: 256KB Flash, 16KB RAM
micro:bit V2:
Processor: Nordic nRF52833
Core: 64 MHz ARM Cortex-M4 with FPU (Floating Point Unit)
Memory: 512KB Flash, 128KB RAM
Connectivity: Bluetooth 5.0

Function of the Interface Chip:

An NXP Kinetis chip (like the KL26Z in V1 or KL27Z in V2) acts as an interface processor, managing USB communication, power, and debugging for the main nRF chip.

AI Overview
The nRF52833 is a significant upgrade from the older nRF51822
, featuring a faster ARM Cortex-M4F core (vs. M0), much more RAM/Flash, support for Bluetooth 5.1 with Angle of Arrival/Departure (AoA/AoD) for direction finding, and enhanced peripherals, making it suitable for modern, complex applications needing higher performance, longer range, and precise location, while the nRF51822 (often seen in older beacons) is a simpler, lower-power chip with a basic M0 core. The nRF52833 offers a leap in processing power, memory, and advanced Bluetooth features like direction finding, making the nRF51822 largely obsolete for new designs.
nRF51822 (Older Generation)

Core: 32-bit ARM Cortex-M0 @ 16 MHz.
Memory: Limited RAM/Flash (e.g., 256KB Flash, 16KB RAM).
Bluetooth: Older versions (BLE 4.0/4.1).
Key Features: Basic BLE, low power, simple peripherals.

nRF52833 (Newer Generation)

Core: 32-bit ARM Cortex-M4F @ 64 MHz (with FPU).
Memory: More RAM/Flash (512KB Flash, 128KB RAM).
Bluetooth: Bluetooth 5.1 (including Long Range, 2Mbps, AoA/AoD).
Key Features: Advanced peripherals (I2S, PDM, High-Speed SPI, USB), wider operating temp (-40°C to 105°C), supports Thread/Zigbee, excellent for location services.

Key Differences & When to Choose

Performance: nRF52833 is vastly more powerful due to its Cortex-M4F core.
Memory: nRF52833 has significantly more Flash and RAM, allowing for complex applications.
Bluetooth Features: nRF52833 supports Bluetooth 5.1, including direction finding (AoA/AoD), a critical feature for asset tracking.
Peripherals: nRF52833 adds USB, High-Speed SPI, I2S, PDM, making it more versatile for audio or complex sensors.
Application: Use nRF52833 for new designs needing advanced features, higher performance, or long-range/location, while nRF51822 is outdated for most new projects, as the nRF52833 offers a better, more capable platform.