Speed & Cable Lengths Max bus length 1200m (at 100kbps) Max transmission rate 10Mbits (up to 12m) Maximum Number Of Nodes RS485 is specified as max 32 devices connected to the bus, although some drivers allow more (2x or 4x)
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CAN vs RS485
CAN (Controller Area Network) and RS485 are both popular standards in fieldbus systems. RS485 only addresses layer 1 (the physical layer) CAN also adds layer 2 (the data link layer) in the OSI model. Both are based on multiple nodes connected to a shared serial bus with one or more acting as a master being possible. […]
.CAN Bus General
CAN bus ("Controller Area Network") is widely used in the automotive, aerospace, maritime, industrial and medical industries. Bus General Microcontroller CAN Bus Pins (Pre CAN Transceiver) High = recessive bus state (bus not driven), Low = dominant bus state (bus is driven by transceiver) Multi Master serial bus. TX and RX pins from the bus transceiver: The CAN bus TX line (pre transceiver) […]
Piezo Sounders
A piezoelectric ceramic element is a sintered body of many crystals (poly-crystals). Distortion of this crystal occurs when a stress is applied to the element either thermally, mechanically or electrically. For piezo sounder applications a metal plate is typically attached to the ceramic element and it is this plate which vibrates due to the expansion and contraction […]
Logic Gate Part Numbers
Good Resources Wikipedia.org/wiki/List_of_7400_series_integrated_circuits
Logic Families
TTL "Transistor Transistor Logic" Basic voltage levels VOHmin (minimum HIGH output voltage) 2.4V VOLmax (maximum LOW output voltage) 0.4V VIHmin (minimum HIGH input voltage guaranteed to be recognised as logic 1) 2V VILmax (maximum LOW input voltage guaranteed to be recognised as logic 0) 0.8V Power Draw a lot of power (individual gates may […]
NTC Thermistors
When using a NTC as a temperature sensor be careful to not running too much current though it, since the current will heat the NTC and introduce a measurement error. For this reason, high value NTCs (10 kΩ or more) are better for thermometers. NTCs are usually not factory calibrated and the actual R25 and B25/100 can […]
HDMI and DVI
DDC DVI borrowed the I2C for the DDC lines, and then the HDMI carried it over. This was a short sighted choice of protocol because they did not foresee the DVI and HDMI would be used way beyond the simple system of one DVD player to one TV. Although both relaxed the max DDC capacitance to 700 […]
Fans
There is no agreed standard connector for PC fans, but there is a most choice. 4 Pin Fan Molex have a special 4 pin fan connector which is designed to accept both 3 pin (no PWM speed control) and 4 pin fans. Line connector Molex 47054-1000, RS 720-5990 Line connector contacts Molex 47054-1000, RS 172-9178 PCB […]
Buck Regulator Inductor
A quick and somewhat dirty way to calculate an inductor value for buck regulators operating in constant conduction mode (CCM). http://electronics.stackexchange.com/questions/49280/how-to-choose-a-inductor-for-a-buck-regulator-circuit