i have a problem with my STM32f205. My I2C worked well but suddenly the SCL isnt able to go HIGH. Instead of 3,3 V he is just able to go 0,6 V. If i flash the STM with a new Code and change the alternate function from the pin to normal GPIO Output, its able to toggle between 0 and 3,3 V. Where is the Problem? Is it possible that the alternate function is defect?
All VDDs of the STM are 3,3 V and all GNDs are 0 V. There is no short circuit.
Related
I really wanted at first an rs232 8-channel relay board that I could command devices to turn on/off with a command string.
All of the ones I found online have the same deficiency in functionality for me: you can't set a subset of relays at the exact time. I can set relay 1 on, and then relay 7 on afterwards, I can set all 8 relays at once, but there is no command structure to pick out the exact leds I would like to turn on/off.
In the past I have dealt with hardware that had a bit-map of the IO pins, and a bit-map of the states and would apply all 8 settings at once. here are some examples:
to set pins 1 and 7 to on and the other pins off (8-bit binary bit-mapping,) send the following byte: in binary: 0100 0001b
to set pins 1,2,3,6 to on and the other pins off (8-bit binary bit-mapping,) send the following byte: in binary: 0010 0111b
I couldn't find any such device to do this so I thought I could make one with a raspberry pi using a simple 8-channel relay board, something like this:
https://www.amazon.com/SainSmart-101-70-102-8-Channel-Relay-Module/dp/B0057OC5WK
but on a Raspberry Pi, I'm running into the same issue: I don't see a way to set the gpio pins as a block command, only individually setting them in a for loop. I looked all morning and can see things like gpioctl, and mmio, but I can't put it all together to a simple proof of concept program on a testboard, any help would be appreciated.
I would really like a solution in C or scripting,
Thanks,
jleslie
I have a Lolin MCU like this Lolin v3
I have a PCA9685 board like this cheap controller
And Im coding in microPython in the nodeMCU device. I managed to attach one of those small 9g servos to the nodeMCU board and controll it. No problem. I want to use a controller since I need more servos, so I connect the PCA like this:
PCA V+ <--> 3v3 in the mcu (5v produce no changes)
PCA GND <--> GND in the mcu
PCA SDA <--> SDA (Pin 4) in the mcu
PCA SCL <--> SCL (Pin 5) in the mcu
PCA OE <--> GND, V+ or open. Makes no difference
Now I downloaded this PCA9685.py and Servo.py from this web microPython PCA controller
I create an I2C like this
>>> i2c = machine.I2C(scl=machine.Pin(5), sda=machine.Pin(4))
>>> i2c.scan()
[64, 112]
So the device is there. The cables are good, the i2c is working. But the servos won't move no matter what. Not even buzz.
I try moving the servo using
servos.position(1, us=1500)
no thing happened.. I connected several servos in several ports to make sure is port 1 not port 0 and those stupid errors.. nothing.
This is the code I'm running at the device right now:
from machine import I2C, Pin
import servo
servos = servo.Servos(I2C(scl=Pin(5), sda=Pin(4))
for i in range(16):
servos.position(i, us=1500)
Any clue ???
Like the title said, I need more GPIO pins or just a way to control a lot leds
So I need to control more than 40 leds, or even more, anyway more than raspberry pi has GPIO pins. So I know that there is extension board for Raspberry Pi that extends the GPIO, that's one way to solve it. If anyone ever had one can recommend it to me.
Another idea that I got was to use led matrix but instead use the same idea, I mean for example led row 1 and column 4 or so, but the leds won't be in Grid, instead, they will be separated with wires. But the problem, if we want to do like that:
X O X
O X O
X O X
where X is on and O is off, it's not possible. All leds will be lit up, not like in the pattern. If anyone has the solution to one of the ideas then please share it with me, thank you for your time!
You want to control lots of LEDs using as few GPIO pins as possible.
Solution
The way to do this is to use a technique called Charlieplexing. The name comes from the inventor, Charlie Allen of the company Maxim, and the technique takes advantage of the feature of GPIO pins that allows them to be changed from outputs to inputs while a program is running. When a pin is changed to be an input, not enough current will flow through it to light an LED or influence other pins connected to the LED that are set as outputs.
use breadboard
for more information go to this link
http://razzpisampler.oreilly.com/ch04.html
I've got a Raspberry Pi Zero W v1.1 set up today and I've been trying GPIO's. Got them (I'll refer to GPIO #3) to output between 3.3v to 0.05v on command using echo 0 > /sys/class/gpio/gpio3/value with direction OUT and got them to read in logic 1 to 0 by connecting pin #7 (GPIO #3) to a ground (will replace with a sensor later on) with direction IN.
My question is: Would you consider this normal that the Raspberry Pi defaults to logic 1 as soon as you enable the export? echo 3 > /sys/class/gpio/export
Can somebody elaborate on why this is? Also, why is this exactly the opposite of this guy's scenario: Reading a sysfs GPIO input pin (direction as "in") always print a fixed value (0)
Kthx
You said there is nothing connected to the pin, yet you read value=1. This is due to internal bias on the input which is weak and can be over-driven by an external circuit if you were to connect something to the pin. The internal bias simply is a large (~1M ohm) resistor to the VCC, so you are reading this bias. Try connecting a 1K ohm resistor from the pin to ground and read it again. It should read value=0 as you were initially expecting.
I'm trying to talk via I2C to the gyro sensor MPU6050 which sits on a GY 521 board. But i can't get the device being detect.
I tested another i2c device (EEPROM) and got the device address detected. So i guess it has to be a hardware problem.
As far as i could find out:
RPi has a 1.8k pullup resistor on SDA and SLC already on board
my GY 521 also has also a pullup resistor (2.2k) on each line on board
Could the resistors be the problem? A good resistor value in sum would be around 5k on each line?
(The wiring should be ok, there are a lot of instructions around the net and i've checked it multiple times. I use 5v on the GY521 since it has a voltage converter)
Any help appreciated!
The problem was bad soldering.
For the record:
Using the RPi pullups in combination with the breakout board pullups works for me.