The Peripherals Page.
Credo.
There is no good definition for microcontrollers.
Usually, they are referred to as microcomputes on a single chip. However, it is relatively rare that a microcontroller forms a really embedded system with no or a few other components. Contrary, it is not uncommon to see a microcontroller in a very complex design.
Therefore, in spite of efforts of manufacturers to integrate as many different subsystems into one chip as possible; I believe, there is always need for a good peripheral to connect... ;-)

These pages intend to give first and rapid information one might need designing a microcontroller-based system. Therefore you will find here clues rather than ready-made circuits, drawings etc.

What can be connected to a microcontroller (ev. microprocessor):

• properly decoupled (RF)/debounced amplified
• galvanically decoupled
• level shifted, Schmidt triggered
• parallel-to-serial, expander circuits (like 8255,6821)
• keyboards, matrices
• sensors
  • switches!, microswitches, magnetic reed switch, Hg (mercury) tilt
  • position (also shaft encoders, "the mouse"; inclination), touchscreen
  • temperature (thermocouple, thermistor), humidity
  • pressure, acceleration
  • chemical
  • "human" (like EKG (ECG) etc.)
  • optical
    • barcode
    • interrupters, also with fibre
    • IrDA, IR remote controllers
  • magnetic (hall)
    • magnetic stripe
  • time measurement
  • ... and analog converted to digital ...

• serially
• parallel bus

• current/voltage considerations, saturation of bipolars, level shifting
• logic-containing MOS switches
• matrices
• actuators
  • motors
  • solenoids

• LED 7seg, smart 7seg (LED and/or LCD)
• LCD few seg/few alpha (7x5) lines
• LCD panels
• CRT

• synths
• complex (SB-like)
• mixer
• MIDI see serial busses

• external program memory
• external data memory, serial, parallel, FLASH (+ the "infinite" alternative), battery backup RAM
• floppy
• HDDs = IDE, SCSI?

• RS232, 485, I2C, CAN, USB, Ethernet, FireWire?, simplex, half/full duplex
• 1wire-2wire-3wire serial, I2C, MIDI
• wireless = IR, RF
• Centronics, IEE488, ISA, PCI

• telephone interfaces
  • level check
  • hook on/off test cct
  • modems
  • DTMF
  • ISDN
• line modems
• wireless (IR, RF, ultrasound)
  • Bluetooth
  • ZIgBee
  • ?WiFi

• serial, parallel
• succ aproximation, Flash, resistor to frequency, ramp time meas A/D +dual slope, sigma-delta
• very cheap resistor array D/A, PWM
• digital potentiometers
• (see also sound chips)

• reset and power (backup) considerations, clocks, Xtals, etc. = all the analogue stuff all around the micros. Also some EMC consideration, black magic debugging and similar.
• frequency synthetiser (PLL)
• physical random number generator
• some math routines, mainly commonly used routines

Other (perhaps more logical) approach

• data (signal) creation
  • sensors
  • timer/clock
• data/signal conditioning
  • amplification
  • level shifting
  • schmidt triggering
  • volt./amp.-to-freq. conversion because of long distance transfer
  • DC decoupling - opto,
  • switches debouncing
  • ...
• signal-to-data (A/D)
• freq.measuring (counting)
• data concentration
  • parallel-to-serial
  • I/O chips (such as 8255)
  • ...
• data storage
  • memories
  • mass storages
  • disks
  • tapes
  • cdrom
  • other
• data processing
  • some sample maths, mainly commonly used routines
• data transfer
  • buses
  • modems
• data output
  • D/A
  • data expansion
• outputs
  • power output
  • actuators
  • displays
  • sound
• misc
  • reset
  • xtal
  • other stuff