5
votes
Accepted
Can a 485 network work if the DE (driver enable) pin of the transceiver is always on?
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 ...
- 57.9k
4
votes
Accepted
How do you do a software reset of the am355x (like on the BeagleBone Black)?
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 ...
- 10.2k
3
votes
Method for Sending Multiple (16) Channels of Duty Cycle Modulated Signal over Medium-Long Distance
Let's get terminology straight first. There are physical links between devices, i.e. communication lines. And there are logical communication channels. One physical link (e.g. RS-485 bus) can support ...
- 13.1k
2
votes
Buying Low Volume Populated PCBs and Handling Passive PNs
Some assembly houses have a stock of generic passives that they prefer, since they can keep full reels of them on hand. Others insist that you provide a manufacturer and part number for every ...
- 6,195
2
votes
Accepted
Flash/obtain ROM code for Sitara on BeagleBone Black
The AM335x ROM is fixed by TI, there is no real reason to need the code. It loads a small executable depending on the bootstrap pins from one of many possible locations including MMC, NAND, UART (via ...
- 1,243
2
votes
How to interface matrix LED with beaglebone black
I bought a LED click board
That board uses an array of WS2812 LEDS which have a built-in controller in each LED.
The datasheet explains the control signal timing and how the signal is cascaded ...
- 14.8k
2
votes
Accepted
Use BBB analog inputs with 0..5V or 0..10V
Use a voltage divider to attenuate the signal. Sometimes its advantageous from an impedance perspective to buffer the signal with an amplifier (but is harder to wire). The attenuation is for 0 to 5V ...
- 88.8k
2
votes
Can a 485 network work if the DE (driver enable) pin of the transceiver is always on?
Using an oscilloscope, we saw that the driver enable (DE) pin was always high, but somehow the Beaglebone was able to normally send requests and receive correctly responses from the other equipement.
...
- 10.5k
2
votes
Accepted
Yet Another question on using GPIO to short a remote push button
This isn't a full answer but may help you sort out your schematic.
simulate this circuit – Schematic created using CircuitLab
Figure 1. A redraw of the OP's suspect schematic.
Draw positive ...
- 180k
2
votes
Yet Another question on using GPIO to short a remote push button
CD4066B is one example of a simple quad switch. It has four switches in it which can be controlled independently.
If you drive control signal A, the IC will establish a connection between Pin 1 and 2....
- 9,461
2
votes
Accepted
Beaglebone Black Power Switch Detection
Your approach of monitoring the VDD_5V going into the AC pin of the PMIC seems OK. There is also the possibility of reading the PMIC Interrupt registers or Status register. Checkout chapter 9.6.4 and ...
- 3,616
2
votes
Beaglebone: Unable to boot with custom cape
LCD_DATA0 ~ LCD_DATA15 configure boot priority during the boot process and are called boot pins. These pins are internally pulled up/down by a set of resistors. According to BBB reference manual:
...
2
votes
Accepted
Purpose for Shunt Resistor on Opto Isolator Input?
The currents that you show appear to agree with a quick circuit simulation I did with LTSpice. Do note that the 1.2K and 200 ohm resistors are not acting like a normal voltage divider. Instead the ...
- 57.9k
2
votes
What is this communication standard I'm seeing? It looks like UART but with a third line
It looks like UART with hardware flow control.
Page 15 in the data sheet states that it supports hardware flow control on the USART https://www.silabs.com/documents/public/data-sheets/efr32mg12-...
- 116
2
votes
Why can't the bootloader save and log messages for us to view later
Or am I missing something that makes this procedure very difficult?
Yes. The bootloader is what loads your operating system.
There's no drivers but the minimal bit you need to load the operating ...
- 100k
2
votes
Thermostats outputs to GPIO then to Furnace
First thing to do is find out if you have black (ground) wire available.
If you do, then make sure you have other colors right by operating thermostat and measuring voltage between other wires and ...
- 13.1k
2
votes
How to generate PWM with duty cycle varying in sinusoidal fashion?
Your circuit won't work because you have a dead short across your supply: -
If you want to approach it this way you need to use a full H-bridge: -
Note that I haven't shown the flyback diodes on the ...
- 473k
2
votes
Accepted
I2C peripheral fails after a single transaction
I have found the issue with the given code after some tedious debugging; turns out the delays given in the library were not enough, and the library failed to clear the bit flags that indicate an error ...
- 49
1
vote
Configuring UART TX and RX pins to accept CAN TX and RX signals
No, UART port does not directly correspond to CAN. In the Beaglebone you have physical pins that can be muxed to different peripherals, say pin E16 can be configured as UART0_TXD or as DCAN0_RX, but ...
- 661
1
vote
Purpose for Shunt Resistor on Opto Isolator Input?
But now, my secondary question is (in general). Are my current values correct?
Your current values seem quite correct.
According the datasheet of the PS2802, \$I_f\$ = 13.5 mA gives a \$V_f\$ = +/- 1....
- 10.9k
1
vote
Accepted
Systems similar to TI's PRUs
NXP's S12X series of processors has an "XGATE coprocessor to achieve higher performance or emulate peripheral modules"...
https://www.nxp.com/products/processors-and-microcontrollers/additional-...
- 179
1
vote
Accepted
Beaglebone Black — Reading multiple HX711 / Load sensors
There are basically two ways to do it:
Connect it directly to BBB and write or obtain software to run it. You say that you have not found examples for it so you would have to roll your own.
Use ...
- 398
1
vote
Beaglebone Black LCD/TFT/display and I2C2
Ask 4D, or the 4D forum.
However, it looks to me that the I2C bus is used only for an on-board EEProm interface. Probably to store/read setup and user data. I would guess that there's plenty of ...
- 3,728
1
vote
Yet Another question on using GPIO to short a remote push button
You want a cmos analog transmission gate.
74HC4066 gives you 4 separate "switches"
The separate switches of the 4066 are very easy to understand, and you don't need a correct schematic to make it ...
- 5,493
1
vote
Design Review: 3.3V Logic to 12V Logic (Uni-directional and Bi-directional)
Since you've attempted to use relays, I imagine that these signals don't switch very fast. If the loads on the 12V side are non-inductive and referenced to ground, then going from 3.3V to 12V is ...
1
vote
DCF77 - No Signal detected
The data sheet says: -
Earth
Operating voltage 1.2 … 1.5 V- (although the German DS appears to say 15 V)
DCF output
DCF output inverted
Outputs 3 and 4 of open collectors npn max. 30 V 1 mA
So it ...
- 473k
1
vote
Is there another way to interface with BeagleBone Black hardware
An option is to use mmap (memory map) and then by utilizing GPIO registers, you can control GPIO pins with higher speed. However, PRU(Programmable Real-time Unit) ...
1
vote
Using Beaglebone Black to prototype commercial product
I think you should leverage your skillsets in providing a functioning prototype and should select a device that already provides all the elements where your skillsets aren't at their peak. Make sure ...
- 78.7k
1
vote
Connecting USB-powered Beaglebone to car's CAN bus through OBD connector using common signal ground
Is the connection presented on the schematic correct?
Looks ok. Though to save cost, it might be a better idea to use a CAN transceiver with 3.3V supply. Example.
Can I connect the Signal ...
- 22.2k
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