ARM’s Cortex M3 is at the heart of Ember’s EM300 line. The EM351 includes a 24-MHz Cortex M3 core, 128 kbytes of 64-bit wide flash, and 12 kbytes of RAM. The EM357 ups the flash capacity to 192 kbytes. They both have a 2-kbyte and 512-byte flash block for storing a boot loader and tokens. The RAM is retained even in sleep mode. The chip can use a low- and high-frequency RC oscillator in addition to a 32-kHz and 24-MHz crystal when changing modes. This allows a fast startup (under 128 µs) without the crystal oscillator. The deep-sleep mode reduces power requirements by 25% compared to prior ZigBee implementations. Software support includes the EmberZNet Pro stack. Peripherals include a six-channel, 12-bit analog-to-digital converter (ADC) with DMA support, 128-bit AES hardware acceleration, a UART/SPI port, an I2C/SPI port, and GPIO. The impressive debug facilities include the standard Cortex M3 debug and trace support plus the ability to capture wireless packets in a non-intrusive fashion. Pricing starts under $3.