SMS Messages

GSM Character Set SMS messages use a different character set to standard ASCII. Characters are 7bits and packed into 140 bytes, giving you up to 160 characters (7 x 160 = 1120 bits, 1120 / 8 bits per byte = 140 bytes). Conversion to and from various ASCII characters needs to be performed in code […]

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Stress Testing Windows Computers

CPU stress test software Prime 95 https://www.mersenne.org/download/ Start test: Options > Torture TestStop test: Menu > Test > Stop Hardware monitoring of CPU load and CPU temperatures HWiNFO https://www.hwinfo.com/download/

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ESD Testing (Electrostatic Discharge)

IEC 61000-4-2 / EN 61000-4-2 This is the basic immunity test method for personnel ESD and is often called up as a basic test method by immunity standards listed under the Electromagnetic Compatibility (EMC) Directive. ESD Simulator tips Direct contact ESD discharge – Pointed tip 4kV typ test voltage. Put tester in contact with a […]

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Ethernet Speeds

10Mbit Ethernet Manchester encoding effectively puts 2 bits in each 100nS bit position so the actual bit rate is 20Mbit1.25 MByte per second, = 0.8uS per byte A basic UDP Ethernet Packet: 8 byte ethernet startup sequence 14 byte MAC header # btyes of data 4 bytes of frame check sequenceThis means for the minimum […]

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HTML

https://cloud-developer.com/category/html/raw-html-data-over-the-wire

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UART Asynchronous Comms

UART Asynchronous TX Example Internal bit clock and the TX output pin of a microcontroller transmittingbytes with the port configured as 8N1 :

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Solving CE Test Failures

A few ideas on how to solve CE test failures… PSU Noise? Try powering the circuit from a battery without the PSU and re-test? This can confirm if PSU is the source of noise. Use a DC power line filter, e.g. Murata BNX016-01 etc If PSU is conducting test noise through it Are low voltage […]

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Tranzorb diodes

Useful to catch / block high voltage pulses passing through connections such as power supply outputs, power and signal lines leaving a product, etc. Connect across the line to be protected and ground.

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Compliance Test Companies

Test houses we or our clients have used and have had good experience with in terms of helpfullness in resolving CE issues should they arise. Element Eurofins Hursley

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Tamper detect circuit

Simple battery backed up, switch released detect circuit Circuit is 3.3V powered and has a battery. We want to detect if the tamper switch is ever released, even when the 3.3V power is off, so that when next powered up the fact that the tamper switch got released at any time can be determined.

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