Author Archives: DP

App note: Implementing secure boot with the Atmel ATSHA204

via Dangerous Prototypes

Securing systems with cryptographic authentication device on boot discussed in this app note from Microchip/Atmel. Link here (PDF)

Most systems that use programmable nonvolatile memory for their operating program whether it’s large or small can take advantage of a secure boot process. Secure boot is a method of ensuring that the operating program for a system is authorized, typically by the OEM that designed and built the system. By ensuring that the operating program is authentic, the OEM can prevent unpredictable system performance, safety or regulatory violations, excess warranty costs, lost revenue, and more.

App note: CryptoAuthentication product uses

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App note from Microchip/Atmel on securing products with hardware level authentication chip. Link here (PDF)

Companies are continuously searching for ways to protect property using various implementations of security; however the cost of implementation can drive companies away from effective hardware solutions to less secure software solutions. With the introduction of the AT88SA10HS/102S devices, affordable hardware security is now in reach and can provide exceptional protection for:
Confidential file protection
– Embedded software anti-cloning
– Development system anti-cloning
– Media transmission encryption
– USB security dongles
– Securing wireless or other radio transmission nodes
– Authentication for data over power lines
– Physical access control
– Electronic lockers
– Hardware user authentication
– Consumable product authentication
– Battery authentication

App note: Custom instrumentation amplifier design

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A detailed design of an instrumentation amplifier found in this app note from Renesas. Link here (PDF)

This application note describes some of the fine points of designing an instrumentation amplifier with op-amps. We will cover how to maintain good common-mode rejection and output signal linearity. In addition, we will explain various filters that can be integrated in the design to provide additional performance improvements.

App note: Battery powered overdrive pedal for guitar effects

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App note from Renesas about building a guitar pedal overdrive effect using only 2 x AA instead of 9V battery, this app note demonstrate the low rail to rail voltage OpAmp SLG88104V in use. Link here (PDF)

Amplified guitars appeared in the early 1930’s. However, at that time early recording artists strove for clean orchestra type sounds. By the 40’s DeArmond manufactured the world’s first standalone effect. But at that time amplifiers were valve based and bulky. During the 40’s and through to the 50’s even though clean tones were prevalent, competitive individuals and bands frequently turned their amps volume up to overdrive status and the distortion sound became increasingly popular. In the 60’s transistor amplifiers started to be manufactured with the Vox T-60, in 1964 and around the same era to further preserve the distortion sound which was very sought after at that time the first distortion effect was born.

App note: General digitally controlled potentiometers

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App note from Renesas on what are digitally controlled potentiometers and their operations. Link here (PDF)

Digitally Controlled Potentiometers (DCPs) brought about a new way to adjust resistance in analog circuitry. Mechanical Potentiometers were replaced by DCPs because of their ability to control resistance digitally using interfaces such as I2C, SPI, Pushbutton, 2-wire, and 3-wire (up/down). Unlike mechanical potentiometers where resistance is set by hand or a tool, the resistance of a DCP is communicated by an interface. This interface receives a value that is translated by the decoder from a binary to a decimal number, which sets the wiper into a corresponding position.

App note: Transformerless power supplies – resistive and capacitive

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An app note from Microchip about two basic ways of getting power from AC outlet to power small circuits and microcontrollers, these involves hazard too due to non-isolation from mains but rewards cost effectivity. Link here (PDF)

There are several ways to convert an AC voltage at a wall receptacle into the DC voltage required by a microcontroller. Traditionally, this has been done with a transformer and rectifier circuit. There are also switching power supply solutions, however, in applications that involve providing a DC voltage to only the microcontroller and a few other low-current devices, transformer-based or switcher-based power supplies may not be cost effective. The reason is that the transformers in transformer-based solutions, and the inductor/MOSFET/controller in switch-based solutions, are expensive and take up a considerable amount of space. This is especially true in the appliance market, where the cost and size of the components surrounding the power supply may be significantly less than the cost of the power supply alone.