Micro B connectors are a nightmare. Very inconsistent footprints, poor materials and build quality, and very weak mounting supports. Often the leads are hidden under the housing and conceal pesky shorts. Almost every Micro B connector we hand soldered eventually broke off the board and usually took some traces with it.
USB C solved all these issues! Soldering it is an absolute breeze. Leads are easily accessible and friendly to solder. It’s made of decent materials, and the footprint seems to be pretty standardized across the market. The mounting posts are solid and strong, this connector isn’t going anywhere.
App note from Vishay Siliconix, giving us tips on powering FPGAs. Link here (PDF)
An FPGA is a device that offers many logic elements – up to 1 million gates in a single device at this writing – as well as other functionality such as transceivers, PLLs, and MAC units for complex processing. FPGAs are becoming very powerful, and the need to power the devices effectively is a key, if often underestimated, part of the design. A straightforward power supply design process can significantly reduce the number of required design iterations for the OEM designer.
The Bus Pirate Vpullup pin supplies a voltage to the on-board pull-up resistors. In the “Ultra” hardware it also powers the external half of the bi-directional IO buffer.
AUX2 (formerly ADC)
AUX4 (formerly 3.3Volts)
0.8-5.0Vout (formerly 5.0Volts)
So far we’ve added voltage measurement to every IO pin and removed the dedicated ADC pin. We also replaced the fixed 3.3volt and 5volt power supplies with a single programmable output power supply (Vout) capable of 0.8-5.0volts output at 300mA. Today we’re going to reclaim the Vpullup pin and dig into the on-board pull-up resistor system.
After adding buffered voltage measurements to every IO pin, we eliminated the dedicated ADC pin and turned it into a general purpose IO (AUX2). Now we’re going to take a hatchet to the on-board voltage regulators (3.3V, 5.0V) and replace them with a robust programmable output power supply.
Bus Pirate Ultra v1a follows the same pinout as previous Bus Pirates. 5 I/O pins (MOSI, CLOCK, MISO, CS, AUX), a voltage probe (ADC), a voltage source for the on-board pull-up resistors (Vpu), two power supplies (3.3, 5.0volts) and ground. While we were building the prototype it became obvious that a few tweaks could make a much more useful tool.
This is the starting pinout. In this post we’ll update the voltage/ADC probe to measure voltage on every IO pin, and free up a pin for general purpose use.
I made some wireless sensors, using BME280 temperature, humidity, and pressure sensors, together with SYN115 transmitter modules. I used these to verify the storage of vacuum sealed “PrintDry” 3D filament storage containers.
Another app note from NXP describing the behavior of the SMARTMOS Dual 24 – 36 V high-side switch devices, at switch OFF when driving inductive loads. Link here (PDF)
These intelligent high-side switches are designed to be used in 24 V systems such as trucks and busses (XS4200). They can be used in industrial (XSD200) and 12 V applications as well. The low RDS(on) channels can control incandescent lamps, LEDs, solenoids, or DC motors. Control, device configuration, and diagnostics are performed through a 16-bit SPI interface, allowing easy integration into existing applications.
App note from NXP about the short-citcuit protection strategies of their MC12XS6 centralized automotive lighting drivers family IC. Link here (PDF)
The MC12XS6 devices include up to five self-protected high-side switches, with its extended protection and diagnostics, to detect bulb outage and short-circuit fault conditions. Additionally, this device incorporates a pulse width modulation control module, to improve lamp lifetime with bulb power regulation at no less than 25 Hz, and address the dimming application (daytime running light).
I decided to build a pogo-pin test jig, and since the approach I came up with was different than the other approaches I’ve seen I thought it would be worth sharing. I’m going to be targeting my laser cutter for fabrication, though I could have chosen to use my 3D printer instead.
Bus Pirate “Ultra” taps an iCE40 FPGA to power a combined Bus Pirate interface and logic analyzer that is infinity hackable. Previous Bus Pirates relied on the hardware peripherals available in a microcontroller, which vary in features and have the occasional bug. With an FPGA we can implement practically any peripheral with all the fixes and hacks we want! SPI, I2C, UART, CAN? Yes! Master or slave? Both! Complex frequency generator? Yup! Full featured JTAG debugger? Don’t see why not!
A big STM32F103ZE (1) microcontroller connects to an iCE40HX4K FPGA (2) through a 16bit bus that can move a ton of data. The fully buffered interface (3) is capable of high-speed signaling from 1.2volt to 5volts. 128Mbit of RAM (4) powers a logic analyzer with a potential maximum speed over 200MSPS. A 32Mbit flash chip (5) stores up to 30 bitstreams with different features that can be loaded into the FPGA by the microcontroller.
This post covers our most recent hacks to the Bus Pirate, created with these goals in mind:
Peripherals that work and can be hacked
Direct interfacing at all common voltage levels
Real-speed bus activity
Built-in logic analyzer
Plenty of space for updates
Continue below to read about the design, or jump to the forum to see the bleeding edge.
Designing a custom lithium battery pack is a fun way to learn about electricity and engineering. Lithium batteries can be used for countless applications including electric bikes, scooters, vehicles, backup power suppliers, off the grid solutions, and much more.
App note from Kionix on the introduction of most common method in determining orientation and rotations in an accelerometer. Link here (PDF)
The fact that accelerometers are sensitive to the gravitational force on the device allows them to be used to determine the attitude of the sensor with respect to the reference gravitational vector. This attitude determination is very useful in leveling or gimballing gyroscopes and magnetometers for use in compass and navigation instruments; determining tilt for game controller applications; and determining tilt or rotation for screen rotation of handheld devices. The method for calculating orientation or rotation depends on the specific application.
Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:
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Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
Facebook PCB Friday. Free PCBs will be your friend for the weekend
This tuner circuit is a quick prototype which I build to test the RDA5807M FM radio tuner IC. RDA5807M is a single-chip tuner IC with RDS and MPX decoder, and it equipped with I2C interface for control. This receiver builds around Atmel’s ATmega16A 8-bit MCU. The output stage of this design consists of AN7147N, 2×5.3W audio power amplifier.
ON Semiconductors guide to cover much higher current capacity from eFuses. Link here (PDF)
The standard 12 V, 5 V and 3.3 V electronic fuses from ON Semiconductor provide overcurrent and overvoltage protection and come in different current limit configurations. As an example, the 5 V NIS5452 eFuse has a recommended operational 5 A current limit. Sometimes the operating current for the user system might be much higher than the maximum allowed current limit provided by the eFuse.
Tips and tricks from ON Semiconductors on how to optimize high output current switching regulators thermal dissipation. Link here (PDF)
As power demand in portable designs is more and more important, designers must optimize full system efficiency in order to save battery life and reduce power dissipation. Energy losses study allows knowing thermal stakes. Due to integration and miniaturization, junction temperature can increase significantly which could lead to bad application behaviors or in worst case to reduce components reliability.
At some point I though about building the smallest PCB for a sensor node that I could. Hence, the ZEN was born. The PCB is small enough to fit on a holder of 2 AA batteries. I have only build a few of these. Here is one reading the soil moisture sensor on basil.
App note from OSRAM on High-power LEDs and their special requirements. Link here (PDF)
In general high power emitters can be driven with DC currents in the range of 1 Ampere whereas most low power products like 5 mm Radials are limited to 100 mA.
As the light output increases with driving current the optical power is raised by a factor of ten compared to standard devices. At the same time much less board space is occupied as fewer devices are needed. On the other hand a careful thermal management is absolutely mandatory because the thermal power dissipation is increasing in the same way as the optical output power. To keep the junction temperature of the chip as low as possible a low thermal resistance is needed and the standard FR4-PCB has to be replaced by a metal core PCB. By this a high optical efficiency of the IRED can be achieved.
The approach I took was a mixed signal one where a capable analog front end would be paired up with a beefy DSP processor to compute the Impedance. Most importantly, in this scheme, the DSP is responsible for discriminating the phase between the sampled voltage and current waveforms; this approach is preferred because it leads to good accuracy and calibration stability.