POV infrared data transmission
idea here is to have a IR led directly pulsing the raw data out and an receiver converting it back to signal.. so this could be transmitted over the rotation contact-less. challenge here is the bit time - we need some very very fast photo detectors…
Contents
ToDo:
- find / decide which parts to test
- add schematics for
- led control
- photodiode / phototransistor handling
bitrate / update-rate calculations
| name | test | value | formula |
|---|---|---|---|
| target_bitrate | 33MHz | ||
| pulse_duration | 30ns | toFixed(1000 / target_bitrate; 0) | |
| pulse_duration_min for low or high state* | 10ns | 10 |
* duration= higher or lower than 50% of transition between GND / VCC
other contact-less connections
- Ethernet over inductive coupling
- Ethernet over fiber
information collection (research)
- Vishay
- Analog Devices
- TI
- Why are most IR phototransistors slow?
- example with explanation to drive a phototransistors (optoisolators)
- Anschluß Phototransistor für high-speed? (with schematics)
- Ronja project
- some ideas and research to optical transmission with leds
-
Driving LED in a Nanosecond Regime by a Fast Operational Amplifier
- MAX3967A - 270Mbps SFP LED Driver led driver for fiber optics MAX3967A: Improving Speed Performance of Slow LEDs Using the MAX3967A with Added Peaking Elements
SN65ELT20 5-V TTL-to-Differential PECL Translator
High-Speed LED driver
- fastest way of doing on/off-modulation of a LED?
- LEDs in fiber optics this link has some really good basic information about how to drive LEDs with high speed… (it contains three similar circuits.)
High-Speed Receiver
Anschluß Phototransistor für high-speed?
Parts
| part | type | angle φ | wavelength | housing | capacitance | rise/fall time |
|---|---|---|---|---|---|---|
| VEMT2020X01 | photodiode | 860nm | SMD GW | 25pF | 2ns | |
| VSMF4720 | led | 870nm | SMD PLCC-2 | 125pF | 15ns | |
| VSMY14940 | led sideview | ± 9° | 940nm | SMD SV | 30pF | 6ns |
| VSMY1850X01 | led | 850nm | SMD 0805 | 125pF | 10ns | |
| TEMT7100X01 | photodiode | 870nm | SMD 0805 | 25pF | 2ns | |
| BSL214N | NPN | DUAL 2.5V | SMD TSOP-6 | 4.1ns + 7.6ns | 6.8ns + 1.4ns | |
| IRLML0060TRPbF | NPN | SMD SOT-23 | 5.4ns + 6.3ns | 6.8ns + 4.2ns |
Vishay source for rise/fall times for photodiodes