rt-thread/bsp/apollo2

Apollo2 MCU是基于Ambiq Micro的Apollo MCU产品系列的第二代控制器。 Ambiq使用专利亚阈值功率优化技术（Subthreshold Power Optimized Technology， SPOT）平台来实现惊人的功耗降低，其功耗通常比性能相近的其它MCU产品降低5至10倍。 Apollo2 MCU采用32位ARM Cortex-M4F微控制器，集成了高达1 MB的闪存和256 KB的RAM，以适应无线电和传感器开销，同时仍留有足够的应用代码空间。该微控制器还包括串行主机和UART端口，用于与无线电和传感器通信，包括加速度计，陀螺仪和磁力计。

Features Ultra-low supply current 10 μA/MHz executing from flash at 3.3 V 10 μA/MHz executing from RAM at 3.3 V

High-performance ARM Cortex-M4 Processor Up to 48 MHz clock frequency Floating point unit Memory protection unit Wake-up interrupt controller with 32 interrupts

Ultra-low power memory: Up to 1 MB of flash memory for code/data Up to 256 KB of low leakage RAM for code/data 16kB 1 or 2-way Associative Cache

Ultra-low power interface for off-chip sensors: 14 bit, 15-channel, up to 1.2 MS/s ADC Voltage Comparator Temperature sensor with +/-2C accuracy

Flexible serial peripherals: 6x I2C/SPI master for communication with sensors,?radios, and other peripherals 1x I2C/SPI slave for host communications 2x UART for communication with peripherals and?legacy devices PDM for mono and stereo audio microphone

Rich set of clock sources: 32.768 kHz XTAL oscillator Low frequency RC oscillator – 1.024 kHz High frequency RC oscillator – 48 MHz RTC based on Ambiq’s AM08X5/18X5 families

Wide operating range: 1.8-3.6 V, –40 to 85°C

Compact package options: 2.5 x 2.5 mm 49-pin CSP with 34 GPIO 4.5 x 4.5 mm 64-pin BGA with 50 GPIO

Board info Apollo2 Evaluation Board（http://ambiqmicro.com/apollo-ultra-low-power-mcu/apollo2-mcu-20170703/）