Embedded Engineering Guides

Longer explanations of the problems behind the calculators: where the rules of thumb come from, worked examples, and what to check on the bench.

• ADC Resolution Is Not Accuracy: LSB Size, Reference Error, Settling and Oversampling

  What a 12-bit ADC really gives you: LSB size, why the reference dominates the error budget, how source impedance limits sampling time, ENOB, and when oversampling adds real bits.

• C Struct Padding on Cortex-M: Where the Bytes Go and How to Control Them

  Struct layout rules on ARM Cortex-M with compiler-checked examples: member order, 8-byte alignment of 64-bit types, what packed really costs on M0 and M3, and safe layouts for packets.

• CAN Bit Timing Step by Step: Choosing BRP, Segments and Sample Point

  How to work out CAN bit timing by hand: time quanta, which quanta counts your clock allows, why 87.5% is not always reachable, propagation delay, SJW, and the STM32 CAN_BTR value.

• Why Your CRC Does Not Match: Polynomial, Init, Reflection and XOR-Out Explained

  The five parameters that define a CRC, check values for common CRC-8, CRC-16 and CRC-32 variants, byte order on the wire, the residue trick, and a method to find which parameter is wrong.

• Fixed-Point Arithmetic in Q Format: Scaling, Multiplying and Not Overflowing

  A working introduction to Q-format fixed point for microcontrollers without an FPU: choosing the format, conversion, multiplication with rounding, the −1 × −1 overflow, and accumulated error.

• Floating-Point Pitfalls on Microcontrollers: Precision, Timestamps and Accidental Doubles

  What single-precision float can and cannot hold, why a millisecond counter in a float breaks after 4.66 hours, why 0.1 added ten times is not 1, and how one missing f suffix pulls in double-precision library code.

• Sizing I2C Pull-Up Resistors: Minimum, Maximum and What Bus Capacitance Does

  How to choose I2C pull-up resistors from the sink current limit and the rise time limit, with tables for standard, fast and fast-mode plus, and how to measure rise time on a real bus.

• How Much UART Baud Rate Error Is Too Much? The Sampling Math

  Where the "keep UART baud error under 2%" rule comes from: mid-bit sampling, the 9.5-bit drift budget, oversampling, frame length, and how to measure the real error on a scope.