The ZX-24r is a powerful microcontroller for your home automation, industrial control, robotics or other embedded systems application. It is a more capable version of the popular ZX-24p microcontroller, the primary differences are an additional hardware serial port and lower power consumption.

The heart of the ZX-24r is the Atmel AVR ATmega1284P microcontroller running at 14.7MHz. It is accompanied by some support circuitry on a 24-pin DIP module that is pin-compatible with the Parallax Basic Stamp and NetMedia BX-24 microcontrollers. However, many advances have been made with respect to those pioneering products in order to provide a more powerful and flexible programming platform.

The ATmega1284P microcontroller internally has 16384 bytes of RAM of which 15744 bytes (15.3K) are reserved for direct use by your programs (including dynamically allocated string data). The remaining 640 bytes are used by the ZX-24r's control program. The mega1284P also has 4096 bytes of internal EEPROM of which 4064 bytes are usable by your program for non-volatile storage. The 128K byte internal Flash memory of the mega1284P is used partially by the control program of the ZX-24r, also known as the Virtual Machine (VM). The part not used by the control program (60K) is available for your program and data.

The mega1284P has other resources available to your program including a high-speed serial port, analog-to-digital converters, timers and other sub-systems that may be accessed using routines in the ZBasic System Library. Alternately, some of these resources may be accessed directly using built-in registers.

You may download a schematic of the ZX-24r (common to all of our 24-pin devices) as a PDF or as an ExpressPCB .sch file. To view the latter, you'll have to download free software from ExpressPCB.

Technical Features

	ZX-24r¹	BX-24P²	BS-2IC²
Manufacturer	Elba Corp.	Netmedia, Inc.	Parallax, Inc.
Package	24-pin DIP	24-pin DIP	24-pin DIP
Operating Temperature	-40 to +85°C	-40 to +85°C	0 to +70°C (industrial version available)
Processor	Atmel AVR ATmega1284P	Atmel AVR ATmega8535	Microchip PIC 16C57C
Power Requirements	4.5-5.5VDC regulated or 7-20VDC	3-5.5VDC regulated or 5-24VDC	5VDC regulated or 5-15VDC
Processor Speed	Up to 14.7MIPS (14.7MHz)	Up to 7.35 MIPS (7.35MHz )	Up to 5MIPS (20MHz)
Program Execution Speed	Up to 270,000 instructions/sec³	Up to 83,000 instructions/sec³	~4,000 instructions/sec
User RAM	15744 bytes	401 bytes	32 bytes
Non-volatile Data Memory	4064 bytes	480 bytes	None
Program Memory	60K bytes (15,000+ instructions)	32K bytes (8000+ instructions)	2K bytes (~500 instructions)
Digital I/O pins	16+3 (note 4)	16+3 (note 4)	16
Analog-to-Digital Channels	Up to 8 channels, 10-bit	Up to 8 channels, 10-bit	None
PWM Channels	Four 16-bit, two 8-bit	Requires application code	One 8-bit pseudo-PWM
I2C Support	1 HW channel, 4 SW channels	Requires application code	2 SW channels
1-Wire Support	Bit and byte level	Bit level only	Bit and byte level
SPI Support	4 HW channels	4 HW channels	No
Synchronous Serial I/O Support	1 to 16 bits, MSB or LSB first	1 to 8 bits, MSB first only	1 to 16 bits, MSB or LSB first
Asynchronous Serial I/O Ports	2-HW, up to 4 SW full duplex	1-HW, 1 SW full duplex	1-HW, half duplex SW on any I/O pin
Async. Serial Flow Control	Yes (HW & SW channels)	No	Yes (SW channels only)
X-10 Command Support	Yes	Yes	Yes
X-10 Receive Support	Yes	No	No
Multi-tasking Support	Yes	Yes	No
External Interrupts	3	1	None
Pin Change Interrupts	All I/O lines	No	No
Analog Comparator Interrupt	Yes	No	No
Interval Timer	Yes	No	No
Exception Handling Support	Yes	No	No
On-board LEDs	Red, Green	Red, Green	None
Floating Point Math	Yes - IEEE 32-bit	Yes - IEEE 32-bit	No
Advanced Floating Point Functions (sin, cos, log, etc.)	System Level	User Level	No
Programming Interface	Serial - 115.2K baud	Serial - 115.2K baud	Serial - 9600 baud
Field Upgradeable System Software	Yes	No	No

Notes:
  1) Items in boldface indicate differences from the ZX-24p.
  2) Information from manufacturer's documentation and website.
  3) Maximum speed based on the instruction b = b + 1 with stack checking disabled.
  4) The additional 3 I/O lines are outside of the standard 24-pin DIP format.
  5) SW means implemented in system software, HW means hardware implementation.
  6) 'User Level' implementation adds code to the compiled program and is slower than 'System Level' implementation.
  Specifications subject to correction and change without notice.

A standard serial port is required to download code to the ZX-24r. If your computer does not have a standard 9-pin serial port but does have a USB port, you may use a USB to serial adapter. Note, however, that some USB to serial adapters are too slow to be useful with the ZX microcontrollers. We have found that adapters based on the second generation FTDI chips seem to work well.

The ZBasic IDE, compiler and documentation may be obtained free of charge via the Download page. See the menu at the left.