Last update 2001/04/22
The Labs - Design & Functionality For The Net
While reviewing items for our HomeNetwork
(Home-Automation) project we reviewed several microcontrollers (aka MCU or uC).
Here some infos we digged out.
- What is a MCU?
- PIC MCU
- AVR 8 bit RISC
- MCU Networking
- MCU Resources
A computer is usually build by several components, CPU, Memory, peripherial
controllers and so forth and all together make up a machine, a computer.
A CPU (aka microprocessor) itself can't do anything. A microcontroller
usually integrates a minimal functionality on one or few chips. As of
2001 several one-chip microcontrollers are available with Flash memory
which are programmable serial via PC, this means, you get a micro-computer
literally in one chip plus few electronic components like quartz and
The PIC serie is developed by Microchip.Com
for quite a while has many tools and application notes and implementation have been done.
Among hobby engineers one chip made its way: PIC-16F84. Its features:
PIC-16F628 is pin-compatible with real UART and 2K Flash memory,
for other PIC microcontrollers (vast selection) visit
- 18 pin
- 1K (14bit) Flash memory
- 13 I/O
- 8 bit counter/timer
- cost ~$8-$10 (4/10 MHz versions)
|Resources|| ||Fortunately a lot resources are available, best use google to search for
application notes, examples, and experiences, or look here:
Another popular MCU has been the AVR from Atmel.Com.
PWM (Pulse Width Modulation) allows D/A conversion indirectly, all
are operational at 0-8/10 MHz, 2.7-6/8V (check datasheets).
- AT-90C2323: 8pin, 2K Flash, 3 I/O, cost ~$8
- AT-90C1200: 20pin, 1K Flash, 15 I/O, PWM, cost ~$8
- AT-90C2313: 20pin, 2K Flash, 15 I/O, UART, PWM, cost ~$10
- AT-90C4433: 28pin, 4K Flash, 20 I/O, 6x A/D 10bit, UART, PWM, cost ~$15
- AT-90C8515: 40pin, 8K Flash, 32 I/O, UART, PWM, cost ~$20
- just to list a few ...
|Misc Infos|| ||The AVR 8 bit RISC are considered 'low-end' MCUs, and there has been
reliability issues as well: Considering the AVR? Read This..., so "Brown-Out" (voltage going below
suggested operation range) seems common problem compromising Flash memory on MCU despite having 'detectors' build-in, many
real-life applications suggest external "Brown-out" circuits, especially in case of AVR recommended.
Another problem with AVRs has been availability, check with your local store; here
in Switzerland the major electronic distributor has them.
One of the next considerations are how to network MCUs together?
Most Application-Notes describe various microcontroller networking approaches:
|LIN|| ||LIN (Local Interconnect Network), short-range, 20kbps, master/slave, 2 wires.
|CANbus|| ||CAN (Control Area Network), 120kbps - 1Mbps, (100m 500kbps, 200m 250kbps,.. 6km 10kbps), 4 wires.
|1-Wire|| ||1-Wire formerly known as MicroLAN (Dallas Semi.), 1-wire (signal+ground), 115.2kbps
|RS-232 / RS-485|| ||RS-232 with UART (or emulated UART), point-to-point, up-to 1Mbps, 4 wires (2-25 wires).
RS-485 with internal/external UART, multi-drop/point, up-to 10Mbps, 2 wires.
|Other Approaches|| ||
|TCP/IP for MCUs|| ||
Hipocrisy of the finest:
"I agree that no single company can create all the hardware and software. Openness is central because it's the foundation of choice."
-- Steve Balmer (Microsoft) blaming Apple regarding iPhone, February 18, 2009
"Things work better when hardware and software are considered together, [..]. We control it all, we design it all, and we manufacture it all ourselves."Last update 2001/04/22
-- Steve Balmer announcing Windows 8 Tablet, June 19, 2012
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