A very popular enhanced X2 PICAXE microcontroller. Favoured in hobbyist projects due to its powerful features and capabilities, but also suitable for more advanced educational use. This is the universal voltage version 28X2 chip (based on the PIC18F25K22).

The 28X2 supports up to 22 inputs/outputs with 16 analogue/touch sensor channels with an operating speed up to 16MHz using an internal oscillator and up to 64MHz using an external resonator or crystal. This chip supports 4 internal and up to 32 external program slots and is capable of acting as an i2c slave device.

All X2 series parts support enhanced features such as configurable i/o pins, ring tone music and touch sensor inputs, i2c, spi and high-speed serial with background receive. Scratchpad memory plus separate Data EEPROM and Data Table are supported.

Click here for more X2 series information.

For more details see the What is PICAXE and PICAXE Pinout pages.

The PICAXE-28X2 replaces the older PICAXE-28, 28A, 28X, 28X1, 28X2-5V (PIC18F2520) and 28X2-3V (PIC18F25K20) chips.

Specification:

Feature	08M2	14M2	18M2	20M2	20X2	28X2	40X2
Memory Capacity (bytes)	2048	2048	2048	2048	4096	4096	4096
RAM (bytes)	128	512	256	512	256	1280	1280
Byte Variables (bytes)	28	28	28	28	56	56	56
Input/Outputs Pins	6	12	16	18	18	22	33
ADC/Touch Pins	3	7	10	11	11	16	27
Max. Freq. (MHz)	32	32	32	32	64	64	64
Serial In/Out	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Infrared In/Out	Yes	Yes	Yes	Yes	Yes	Yes	Yes
I2C	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Tune (ring tones)	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Parallel Tasks	4	8	4	8	1	1	1
Program Slots	1	2	2	2		4	4