48 votes
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Why did USB win out over parallel interfaces?

At face value sending 8 bits at once seems faster than sending just one at a time. In reality, there are other factors that affect parallel transfers. The Achilles heel of parallel is the wait time ...
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  • 6,851
37 votes
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Mysterious LCD interface without wires

The little piece of rubber you removed IS the connector. Elastomeric connectors look like a piece of rubber and are commonly called "zebra stripes" because the conductive carbon stripes in the ...
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  • 58.2k
25 votes

Why did USB win out over parallel interfaces?

At the time of its introduction, USB was quite slow by today's standards. Operating at 1.5 Mb/s it was designed to replace even slower serial, parallel, and other low-speed interfaces that were used ...
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  • 7,613
20 votes
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Can someone explain this microcontroller ADC interface (for reading solar panel voltage)?

What is the role of the pnp transistor network? It's a differential voltage to current converter followed by a load (R34 and R35). The voltage between P+ and P- sets a voltage across R31. This (minus ...
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  • 384k
14 votes
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Effects of test patterns

Both patterns are necessary. AA/55 causes no net bus current in the transitions, pairs of lines are effectively differential, so there's no ground current in either driver or driven ICs. Alternating ...
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  • 141k
13 votes

Why did USB win out over parallel interfaces?

jwh20 has already given a number of reasons. I would also add that parallel cables can be annoyingly fat when compared with USB3. Parallel cables can be problematic at very high speeds. Unless every ...
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  • 14.8k
11 votes
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Are there any commercially available PLC's that can compile/ download programs through an API?

You can definetely use a PLC for this. Except, you don't want to change the PLC code for each "smoothie recipe". You should write a PLC application that reads recipes from any source, like sd cards, ...
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9 votes
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Why are contacts missing on some of these M.2 modules?

The contacts are missing because they're not used. The A-key variant of the m.2 spec has provisions for display port signals while the E-key variant drops the display port and adds SDIO, UART and PCM (...
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  • 3,569
8 votes

MCU - Minimum list of external components

Some microcontroller indeed only require a bypass cap to operate. Others require some kind of external clock, like a crystal, resonator, R-C, or a digital signal fed in from elsewhere. Newer micros ...
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8 votes
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MCU - Minimum list of external components

In MCUs why do I need any other component except maybe a voltage regulator and an external clock? Some of the extra components are actually recommended, even for a minimum complexity design: ...
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8 votes

Is using the CH340G on a commercial product a horrible idea?

There is an Apple supplied driver for the CH340 included the recent versions of MacOS. "AppleUSBCHCOM".
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7 votes

Interfacing with SATA in embedded systems

The above answer is quite good already, but an alternative approach if your micro-controller is too old/slow/dumb for even USB host or USB-OTG is to use a software (bit-banged) P/ATA interface with a ...
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  • 4,138
7 votes
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Interfacing with SATA in embedded systems

SATA is not a simple thing. SATA peripherals are offered through either PCIe to SATA converters, USB to SATA bridges, or the processor will have an on-chip peripheral. You need to go pretty high-...
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  • 3,538
7 votes
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Understand an I2C clock line implementation

This is related to a feature of the IIC protocol called clock stretching. If a peripheral device is unable to process data from the bus master in time (or prepare its output to be transmitted back to ...
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  • 13.8k
7 votes

Why did USB win out over parallel interfaces?

Is it a matter of USB being both hardware-simple and "fast enough"? IMO yes, it was cheap enough and fast enough, but that is only part of the story. Equally important IMO was it's general ...
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  • 19.3k
7 votes

Why did USB win out over parallel interfaces?

Other answers are good, but they all miss two things. First, USB carried both power (about 2W at first, up to 100W for modern versions) and data in one connector and in one (thin and manageable) cable....
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  • 5,593
7 votes

I want to send F12 keyboard command through STM32F0 to PC

Change your STM32 firmware so that the device is seen as a HID device to PC, not a virtual COM port (UART) to send key presses. Computers with security software on them might reject a custom HID ...
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  • 2,149
6 votes

Meandering traces necessary for 24-Bit parallel RGB LCD interface?

The rule of thumb is that signals travel at 2ns per foot in standard PCB material. That's roughly half as fast as the speed of light due to the effect of the PCB dielectric material. 180psec per inch ...
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  • 590
6 votes
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How to design GUI for my embedded design

This depend on which operating system you are using. If you are on linux, i would recommend you using gtk/glade. Install GCC and other basic requirement,then install GTK library Install Glade in ...
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  • 1,666
6 votes
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How do scanned interface inputs work?

The trick with keyboard matrices like this is the fact that outputs can (on most microcontrollers) be in three possible states - HIGH, LOW, and High Impedance (Hi-Z). When an output is in Hi-Z mode ...
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6 votes

MCU - Minimum list of external components

I assume you're talking about prototype boards here. Those are made complex to make prototyping and debugging easier: they tend to include as many features as possible, limited by the fact that they ...
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6 votes
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Is there a way I can convert from USB to LVDS UART (~1Mbps)?

Typically an UART does not include a PHY, and thus any external PHY can be used for implementing the communication bus. So feel free to select any suitable PHY for this, there are a lot of PHYs that ...
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  • 89.2k
5 votes

Are there any commercially available PLC's that can compile/ download programs through an API?

I will assume that this is a pretty simple task for a minimal plc, rather than something using advanced industrial PLCs I will also assume that this is industrially useful, which is to say, that the ...
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  • 5,058
5 votes

What exactly do D+ and D- on a USB connection do?

The D+ and D- transfer data between host and device. They are also used for initial plug-in detection so host knows when to start enumeration with device. Differential just means that both data pins ...
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  • 89.2k
5 votes

What factors does the set-up time and Hold-time for an interface IC depend on?

Setup and hold are influenced by the logic speed, the amount of internal skew between the clock input and the destination logic, and the skew between the signal inputs to be sampled. Faster logic ...
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  • 40.5k
5 votes

Effects of test patterns

From an electrical perspective AAh and 55h are preferred to test a worst case cross-talk in addition to delay effects. Testing other patterns is also beneficial for instance FFh to 00h will consider ...
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  • 2,577
5 votes
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I2C Level translator 5 V to 1.8 V using MOSFET, output look weird

I2C output is an open drain output. It means it can not provide 5V at output. It can only switch between 0 (low) and High-Z (high - in this case pullup resistor provides 5V at the line, and not i2c ...
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  • 401
5 votes

USB Communication

D+ (or D- for low speed) is pulled up by an 1k5 resistor. Thus the current into the LED messes up "device attached" detection. Once enumerated, all devices get the SOF token every ...
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  • 9,620
4 votes

What is a digital video port?

As far as I know, there is no DVP spec but the pinout seems to be something of a de facto standard, even though part manufacturers doesn't always call it DVP. That is, there is a pixel clock, some ...
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