# Tag Info

10

The BBB uses a TPS2051 USB Power Switch. It limits the USB Host port power to 500mA on the high end. The power is drawn from the same system bus that powers the rest of the 5v parts, the 5v input port. The BBB needs 1A for normal function + a low current usb device (keyboard, mouse, things that draw little current). Using a Cape or a high current USB device ...

10

The BeagleBone Black is a single-board computer (SBC). It contains a AM335x ARM® Cortex-A8 which is a microprocessor (not microcontroller) with some peripherals, including two 32-bit 200 MHz co-processors intended for real-time processing. The distinction between microcontroller and microprocessor is that the program memory and peripherals are ...

6

Unless you know explicitly otherwise, assume the maximum power is 100 mA. If your external device isn't just using the USB interface for power, and is actually enumerating to the beaglebone properly, it can request up to 500 mA under standard USB. If the beaglebone supports some of the non-standard USB-2.0 high-current charging profiles, any device that ...

6

There is concept called device tree overlay and you can think of it as request for specific pin setup on the device itself. Some pins on the board are by default dedicated for specific purpose, SPI or I2C or just general purpose but some like CAN need to be defined to be used and that's the thing we need to do. Folder /lib/firmware contains list of pre-...

5

You don't normally connect 1-wire devices to UARTs. So you don't need to set a baud-rate. See Beaglebone Black 1-wire or ditto with Arch Linux As an aside, 1-wire support is standard in the Raspian OS used on the Raspberry pi, it seems somewhat easier to use.

5

It is quite possible that the state with the driver always on would allow communications to work in both directions due to the overall current limit and effective output impedance of the driver. You do want to correct this however because the driver in this condition will be under unnecessary stress and drawing way more current from your power sources than ...

4

Given that you're talking about using the 'Bone in an industrial application, I'd probably suggest using optocouplers on your inputs. I'd probably use a bank of eight 4N35s. You could also find an optocoupler chip with multiple gates but the 4N35 is cheap and ubiquitous. An optocoupler with open collector output (the most common type) would probably require ...

4

The biggest risks are that they destroy the equipment, not that they get hurt. At least not until you introduce them to soldering irons! I would recommend not using lithium ion batteries for power - since they can explode if shorted. Regular AA batteries will get hot if shorted (enough to cause burns/fires after awhile) but arent likely to explode. The ...

4

If your BBB is functioning, and you want to write an image to a microSD card, then yes, you can do it with the BBB. You can place your image, as a file, on any USB storage device (formatted as MSDOS / FAT32 / VFAT / whatever you call it). Then mount that device, and use DD to write the image to the SD card: $sudo mount /dev/sda1 /mnt$ sudo dd if=/mnt/...

4

Common issues that came immediately to mind: Ground connection: you need a shared ground to get a usable communication, this gives very weird issues like the ones you describe Unstable clock on either side: as UART has no clock sharing mechanism the clock must be fairly well defined and may not drift much. If you are running from an internal RC oscillator ...

4

The best answer is to use a linear pot in the first place. Yes, you can correct the logarithmic nature of the audio taper pot to get linear pot position. However, you will lose resolution at the low end since the output voltage varies slowly with pot position there compared to the high end. You will have to experiment to determine the compression range of ...

4

Here are some ways for a microcontroller to produce analog signals: Built in D/A. Some have these, although they are not common. Filtered PWM. If your bandwidth * resolution requirements are low enough, this is a easy way to get analog signals. Many microcontrollers have PWM generation hardware built in, and you can trade off the resolution with the PWM ...

4

The PRM_RSTCTRL register has bits that let you directly reset the chip from software... This register is located here... So from Linux, for example, we can execute a cold reset by executing the devmem2 command like so... devmem2 0x44e00f00 W 0x02 ...and it will dutifully reset before the output line is finished printing! NB: If you are thinking you can ...

3

The data line in a string of WS2812B chips is not a shared bus as it might appear. Instead, each WS2812B retransmits each bit it receives down the line at full Vcc voltage so there really is not any "fade" with respect to voltage as you go down a string. If the first pixels is seeing enough voltage to see the bit, then all the other pixels downstream should ...

3

To try to get closure on this, and for my own sanity, I read Section 5.4 "Power Management" of the the BeagleBone Black System Reference Manual (BBB_SRM), Rev-C.1. It says BBB uses two devices to supply the board with power: TPS65217C has a Vin (Max) 5.8V LDO TLV70233 has a Vin (Max) 5.5V These are operating voltages. The BBB_SRM says the "external ...

3

There is a schematic available here: http://elinux.org/Beagleboard:BeagleBoneBlack#LATEST_PRODUCTION_FILES_.28C.29 See page 4. Looks like J1 (the UART0 serial port) has only three of the six pins connected - ground, TX, and RX. The others are NC, so you can apply any reasonable voltage to them. Looks like it is designed to work with a USB to TTL serial ...

3

It ended up being the second i2c bus that I needed to use. As you can see below, 0x70 is the "chip address" available on bus 2! UU is signifying something unavailable or busy. After this I was able to follow the nice instructions here, but using bus 2. Specifically, i2cset -y 2 0×70 0×21 i2cset -y 2 0×70 0×81 i2cset -y 2 0×70 0xe0 for starting ...

3

The Raspberry Pi will do everything you need, and I can't imagine the BeagleBone being any simpler to set up. All you do is flash an SD card (with the very simple Win32DiskImager in Windows, for example), plug it in and SSH to it. Or use the HDMI port with a keyboard if you prefer. Are you plugging the 4G dongle directly to it? If not, be aware that the ...

3

Calibration is really just a case of finding the "zero point" value (which you have identified) and subtracting that from any future readings. That's basically all there is to it. Sit the unit on a stable flat surface, take a number of readings, create an average of them, and use that as an offset value to apply to all your future readings.

3

Most thermocouple signal conditioners (except the cheapest and nastiest) provide galvanic isolation both between the thermocouple and the output/power. If you have an grounded-junction thermocouple, then isolation is recommended. If you have an ungrounded junction sensor then you may be able to get away without isolation (but it's often bad practice, ...

3

Based on Ubuntu linux on BBB, but other Linux will work similarly. The user LED mode can be accessed using the following command: echo none | sudo tee /sys/class/leds/beaglebone\:green\:usr3/trigger > /dev/null Where none can be replaced with one of the following: none nand-disk mmc0 mmc1 timer oneshot heartbeat backlight gpio cpu0 default-on ...

3

I have seen similar issues with the beaglebone black. Below was my hardware and Software configuration. Hardware: Beaglebone Black A5C, 4D System LCD Display, USB cable, old 5V 0.8A cell phone charger re-purposed. Software: Angstrom with Embedded QT or Android 4.2.2 (Jelly Bean). Ubuntu base host system I found that the System was resetting when the ...

3

The ST-Link is basically just a STM32F103 which will interface to the PC on one side and the MCU under development on the other side and download new code to it. I haven't seen a firmware or source code available to build your own ST-Link, so I guess it's still closed. But considering that a Nucleo Board contains a ST-Link and costs only 10 bucks, it's ...

3

Does my schematic make sense? Are there any glaring loopholes The most glaring omission is the fact that this is an OmniGraffle block diagram, not a schematic. A reasonable schematic would show all connections and components. For the purpose of de-bugging (to see waveform quality, rise time etc), I bring out the main SDA, SCL lines and the switch lines ...

2

Ok, looking at the inputs and outputs you want to use, I think the 4x4 driver IC you suggested is overkill for the application. For inputs, there is a variant of that magnetic position sensor with a TTL output which you should be able to interface directly. If I've understood what you mean about the 24V input switches, a simple resistor network should scale ...

2

In terms of efficiency, this is about as good as it will get. The most efficient method of transforming the voltage from 12V to 5V is to use a buck converter as opposed to a linear regulator. The UBEC is a buck converter. For power levels in this range, an efficiency of over 90% is considered good. If you were willing to search around for a custom buck ...

2

It appears that the reading has already been scaled by the software, since the 315 ADC reading you are seeing is very close to the 312 you'd expect with a room temperature of 31.2°C (which, in turn, seems about 10°C too hot for comfort, but that's just my opinion). As you've found, you only need to divide the number (which is the mV) by 10.0 (mV/°C) to get ...

2

Strangely it seems as though the Arduino is outputting voltage over both RX and TX, while the BBB is only outputting voltage on the TX line. My guess is that the bi-directional LLC isn't able detect which direction communication is supposed to happen, and so the BBB isn't able to transmit to the Arduino. This Sparkfun LLC is the same as the one I'm using ...

2

Here is a mosfer driver version, I added a zener to limit Vgs to about 15v since the input can range up to 20v which is usually the max Vgs spec and can damage the mosfet (check yous mosfet specs, you may need to use a lower zener value). simulate this circuit – Schematic created using CircuitLab Vgs can be as low as 5v so you should select the ...

2

If you search for "connectivity attributes" in the TRM, each peripheral has a table listing it's attributes. Each table is basically a list of all the signals used to control each peripheral. These tables tell you where each peripheral gets it's power from, which clock signal it can use, the names of its reset signals, the types and names of its interrupt ...

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