I have a raspberry pi, I want to use one single pwm channel to control a rgb led. There are 2 pins available for pwm0. So I connected red led on first pin and green led on second pin. I connected the blue one on a gpio. When I enable pwm0, the red and green leds are on. I would like to control them individually. I know it will be same period and duty cycle but is there a way to turn one pin off without disabling the entire pwm channel ?
You need to provide more information, such as a code snippet, the library you are using and the schematic. You can find more information on this specific stackexchange thread for raspberry: PWM on Raspberry. You must be having trouble configuring your pins. For sure, you are able to do it.
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I'm setting up a Raspberry Pi 4b with a number of Adafruit chips, and thus have used their CircuitPython library to control SPI communication. They've conveniently set up a way to use any GPIO pins as chip selects, but as a result I had no idea that there are two hardware chip selects on the Raspi (CE0 and CE1 on GPIO8 and GPIO7 respectively). I have already wired these pins (GPIO7&8) with the intention of using them as GPIO outputs, but I've noticed I GPIO8/CE0 is connected to the SPI clock.
Adafruit actually mentions that the NO_CS flag doesn't work in their documentation, and I can't seem to find anything useful online.
How can I disable the hardware CS pins? I know the SPI_NO_CS flag in SPI_MODE is already a bug in the spi-bcm library, and I found this patch, but I'm not sure if it would work (I think CircuitPython utilizes a hardware CS?), let alone how to apply it.
I have an (Adafruit Feather Huzzah) ESP2866 WiFi module which has an (EN) pin to disable the 3v3 output on the chip. This pin is pulled up by default and normally you would just connect it to GND in order to switch off the 3v3 regulator (and disable the peripherals).
What I am trying to achieve is that when the ESP2866 is in "Deep Sleep" mode that the 3v3 output is disabled. Ideally if there was a pin that was pulled down by default when the device is asleep then I could just hook that into (EN) pin but I don't think this exists. However, there are pins that are pulled high by default when the device is fully awake.
What I was considering doing was using a high value resistor to create a weak pull down on this pin by using this to join GND to (EN). Then I would also directly join another pin that is pulled up when the module is on to "cancel out" the pull down. I have a feeling that I might need to end up using a transistor (or a few components) to toggle this low.
Reading the Adafruit forums I have since discovered that pulling the EN pin also switches off the ESP2866 internal circuitry so it will never come back out of deep sleep. On this basis there is no solution to this specific question as there will never be a high pin (without some form of external circuitry).
Thanks to those who bothered to read.
I would like to know if is possible to use an MCP23017 16 bit I/O expander with a MCP3008 ADC and read the voltage with a Raspberry Pi 2. I want to use the ADC as an I2C device. I would like to do this so I don't have to run the program a 'root', so I'm thinking that running the ADC as an I2C device will fix this problem. I'm looking for help with how to wire the system as well as programming it. I'm using the Python 3 editor. The existing program I have will be used to plot a sine wave generated by a AD9850 DDS module who's signal is amplified and fed into a device. I want to measure this voltage. I know how to use a voltage divider, but am having trouble coming up with a way to read it. The measured voltage value needs to be stored as global variable that can be passed around the program. Right now I'm mainly concerned with not running the program as a root, turning the ADC into an i2c device, and storing the voltage as a global variable to be passed around in an existing program.
I have not worked with any kind of I2C TO SPI converter. Still, you can use some I2C to SPI bridges if they work, I just googled it, but that can cause wiring problems.
I can suggest you the same ADC MCP series with I2C interface.Thus, the further I2C connections with MCP23017 expander and then the Raspberry pi would be easy.You can go through various analog to digital converters that can be I2C interfaced with their codes in python or java for pi like MCP3425, MCP3426, MCP3427, MCP3428. You can easily find them or also check control everything as that would be easy to interface using I2C cables and adapters preventing connection or wiring problems.For codes: https://github.com/ControlEverythingCommunity?utf8=%E2%9C%93&query=MCP34
The following codes for MCP_23017 can also help you code the way you want easily with expander being connected to pi:https://github.com/ControlEverythingCommunity/MCP23017_16-Channel.
I think this would solve your problem!!
Thanks.
I'm working on a project with Android and Arduino and am trying to figure out how on the Arduino side to tell if the Bluetooth is connected or not.
I'm using one of these Bluetooth Modules to connect. I know I can send a command through Android, but I'm trying to have an action happen automatically when they connect and not have to run a background application on the Android if possible.
Using the module supplied and nothing else you cannot: notice the module has four connectors:
Power (Vcc)
Ground
Tx (send)
Rx (receive)
Given this interface the only way to determine whether the bluetooth module is paired is to send something to the paired device and have it respond in such as way that your Arduino knows that it is connected. For instance, if your Android program always responds with "Hi there!" when it receives a string "Hello?", then by seingin "Hello?" your Arduino will know that it is paired with your Android phone/tablet. Your Arduino could poll (send the interrogation string) every minute (or every five seconds) to see if it is paired with your device.
There is a better way, but it will require some soldering on your part. If your module is HC-03/HC-05-based, then the PIO9 pin is the "paired indicator LED" (see datasheet here). You could connect that pin to an Arduino input pin and read the level: reading digital 1 will indicate that the device is paired, while reading digital 0 will indicate that it is not. It is possible, though not certain, that the pin on your module labeled STATE is exactly this kind of a pin, i.e. it indicates the paired status. Unfortunately. this pin it isn't connected to the header, so you'll have to solder a wire to the correctponding pad to connect it to your Arduino. You should test it first by connecting a multimeter in voltage mode to that pad and measure the potential between that pad and ground in paired and non-paired state. If this is the pin that responds to the paired state then you are golden. It might be that it indicates power (like the HC-03/05 PIO8 whilc blinks when on). If it turns out that the STATE pin is not the pairing status, then you should request a datasheet from your supplier, and use that to find the status LED connection: one is likely to exist. Once you found the correct pad, verify its function using the voltmeter again. Then solder a wire to that connection and read it from your Arduino.
IMPORTANT: Make sure that your Arduino never puts out a digital 1 on the Arduino pin connected to the bluetooth module status pin: these bluetooth modules run on 3.3V, and connecting any unprotected pins to 5V will be damaging. The Vcc and Txd pins are voltage shifted in the module you bought, but the LED/Status lines are likely not to be. So if the Arduino pin connected to "status" on your Bluetooth module is configured as output and you digitalWrite(HIGH) to it, you will likely damage the Bluetooth module.
Unfortuntaely, the HC-05 will switch states when paired, but won't output a 1 until it's actually connected to something.
For instance, I can unpair my phone from the HC-05, pair again, and then the LED will change state, but the output of the STATE pin is still 0. If I open up an app, and connect to the device manually then the LED, and STATE pin will change state. The LED will periodically blink twice, and the STATE pin outputs a 1 to the Arduino.
If you would like to read the the value of the STATE pin, connect a wire to any of the inputs to the arduino, and code Serial.println(digitalRead(inputPin)); inputPin being the wire to the input of the Arduino.
I've been fighting this thing for months, and have yet to find a way to make this thing automatically connect to my phone. It won't even allow for me to connect to it from my phone to the HC-05 unless I download an app onto my Android. It's possible to bind the HC-05 to a certain address, but even this did not work for me. I want to mess with the "AT+CLASS" command, but the documentation behind the instruction has hindered me thus far.
From the HC-05 datasheet we see that the connection status depends on the output from PI09. Apparently sending "AT+BIND?" to the module will return the status of PI08 & PI09 in the form,
"+ POLAR=PI08,PI09" however this makes no sense to me because in order to get this you must enter AT mode and entering AT mode will disrupt the paired connection, hence it will always send PI09 marked as "not connected".
THUS in order to see if the connection is still live from the arduinos POV I can only see 2 feasible ways:
Program arduino to, every so often, send a "hello?" and if it doesn't receive the expected "Hi back" response, then it is to assume that it isn't connected.
Connect PI09 to an arduino input pin and read it's value whenever you want to check if the connection is live or not
AT+STATE? will return the current state of the connection. Yes you will need to enter at mode, that is done by bringing up pin 11 HIGH on the HC05 module. It does require soldering but it's kinda worth it. It then allows full AT control of the device, then set it LOW to return it to normal working mode.
Another option, which I don't fully understand, is the AT+MPIO? command, which returns the state of all the pins in some strange masked format I don't understand yet.
I use the first option above so that I can terminal (Bluetooth) from my phone to the HC05 and switch on a led/relay etc (ie bring up pin 2 to HIGH) on the HC05. This required entering AT mode (pin 11 HIGH), sending the command AT+PIO=2,1 and then setting pin 11 to LOW to return to normal working mode.
Note: I noticed I had to put a 200ms delay in between high and AT and LOW commands. Angela's solution is nice - I use a cheap XBEE Bluetooth module (HC-05 Bluetooth Bee Master & Slave Module with Bluetooth XBee for Arduino uk2015) 2 units(HC05/6) for 5Stg which are laid out in XBEE format - handy for the 3.3v.
I'm using a Virtex 5 FPGA and want to have a few +5/0 I/O pins to communicate with a microcontroller. The only peripherials I've used on the board so far are pushbuttons and switches and no one I've asked seems to know the simplest way to do this I/O. I've looked around the board specification but haven't found any simple way of doing it. I would appreciate any advice you might have.
This is not an easy thing to do. If you don't have the schematic of the board, then you need to get volt meter with some fine pitch probes and reverse engineer the board.
It is pretty easy if you have 2 boards, with one board it can be really hard since the BGA signals may not be connected to a via and therefore not available on the bottom of the board, and even if they are, then you don't know exactly which pin they are connected to. But with some luck, you can find them since the VIA can only be connected to 4 possible pins surrounding it!
The first thing you need to do is to identify your chip, find the BGA print of the IC from Xilin'x web site.
If your board has some buttons already, then if you are lucky, those signals may be routed to the pins of the FPGA that are available on the bottom of your board. Here are the things you need to do:
Make sure you have good ESD protection to perform these test
Put your voltmeter into 'buzzer' mode
Check the pins of your connector and find out how it is connected, see if there is a pull-up and/or pull-down resistors on the board
when you find the 'active' pin of your connector, start connecting the other probe to the VIAs one by one
When you hear a buzz, make a note of the position (guess or measure the distance between the side of t he IC and the location of the via)
Identify the 4 possible pins that the signal can be connected to
Write a code to get all those 4 signals and connect them to ChipScope
In Chip Scope, capture all 4 signals and see which one is the one with the right connection!
alternative, you can create a design with inputs only, capture all the inputs and put them into a memory block and create a trigger logic to capture all the signals whenever any of the inputs changes, after lots of work and analysis, you will find the correct pins.
Anyway, these are just crazy ideas since this is a really difficult thing to do without having the PCB info of the board.
Good luck with your hacking.