What I've been trying to do is send UART communications from an STM32 L152RE Nucleo board to an ESP32, however when I attempt to send these communications I get nothing on the ESP serial monitor. What I am able to see is the STM32 sending messages to its own serial monitor which is great but not what I want.
What I've read so far is that UART 2 is connected to ST-Link so that it can do specifically what I've been witnessing and it explains how this can be reconfigured to allow for the messages to be sent to a peripheral UART device but I'm not sure exactly how to do that.
So in the picture below it says to do this I need to "turn off" SB13 and SB14 and "turn on" SB62 and SB63. I don't really understand how to interpret that, other than to mean "remove resistors from SB13 and SB14 and Place them on SB62 and SB63", is this correct?
I know there are another set of UART pins on the board, can I use those instead somehow?
Your guess ist correct. "SB" means "Solder Bridge". It is just a pair of pads which can be connected with a solder ball, like a simple jumper. Setting SB13 to ON means to connect the pads with a solder ball, setting SB62 to OFF means to remove an existing solder ball connection.
Using a different USART is even easier. Have a look at the STM32L151xE Datasheet to find out that e.g. USART1 is available on pins PA9 (TX) and PA10 (RX). According to user manual of the NUCLEO-L152RE board these pins are available on the ST morpho connector CN10: PA9 at Pin 21 and PA10 at Pin 33.
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Is it possible to send out a custom message frame on I2C dev from Linux? I am using an i.MX7D board and i would like to use "/dev/i2c-0" device like a simple "serial tty" to "write(fd, bytes, count)". My goal is to send out a single byte for example 0xAB on I2C without any specific slave address and without automatic stop/start bit inserting in my frame.
So i like to make my full custom I2C frame then send it out from Linux. Is it possible, is there any user-space programing techniques in C/C++, Python or any API for it in Linux?
No you can't, because this is limited by the hardware, if you are using the I2c interface, the hardware will limit what you can do.
One way to try is that you can use gpio to simulate i2c or any interface you want to. Many chips support setting the i2c interface to gpio, then you simulate a clock with one gpio, and simulate high and low level with another gpio.
But I don't recommend it, because if you don't follow the i2c protocol, you can't communicate with other i2c devices
Connect two GPIO lines to the I2C bus in addition to the I2C interface. Normally, these will stay tri-stated. When you need to send the magic byte, enable them to send clock and data, then disable them. These won't interfere with I2C, which only drives the bus when transmitting.
Using pin 26 for ADC seems to be discouraged in Toit.
From what I can see on https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/adc.html pin 26 should have an ADC converter, so what is the reason for that?
The ESP32 is limited around ADC2:
Since the ADC2 module is also used by the Wi-Fi, only one of them could get the preemption when using together, which means the adc2_get_raw() may get blocked until Wi-Fi stops, and vice versa.
Therefore I suggest using ADC1-pins if WiFi is used for connectivity.
Since All ADC2 Pins Can't be used while using WIFI, You can use ADC1
GPIO32 ADC1_CH04
GPIO33 ADC1_CH05
GPIO34 ADC1_CH06
GPIO35 ADC1_CH07
GPIO36 ADC1_CH0
GPIO39 ADC1_CH03
Check this video to learn more about esp32 pins and assigned pirepherals:
https://www.youtube.com/watch?v=LY-1DHTxRAk&t=546s
I want to create a basic project in Vivado that takes a value that i input to a client, which is sent to a server I made (in C), and then the server writes that value to a peripheral in Vivado, and then that data in the peripheral is sent to an output pin that assigns to LED's, making the LED light up.
Basically I want to go from client-->server-->peripheral-->LED lights up
For example, in the client (a GUI) I want to give it a value such as 0011, which is received by the server. Then the server writes that value to the peripheral which will then make, in this case, LED0 & LED1 not light, but LED2 & LED3 will light.
I know how to make an AXI4 peripheral in Vivado, and the client-server (TCP/IP) has been made. My question is what code/design block I would need to then take the data written to the peripheral and assign it to the LED's?
Should I make the peripheral a Master or Slave? Overall confused how should i proceed from here. I am using a Red Pitaya (Xilinx Zynq 7010 SoC) connected by an Ethernet cable to my computer.
Also, I thought of running the program on the Red Pitaya by loading the bitstream on to it (using WinSCP) by running the command
cat FILE_NAME.bit > /dev/xdevcfg
in PuTTY (connected to the Pitaya by IP address), then running the server on the pitaya, and then sending the signal from the client for the server to receive. Is that the correct way of approaching it?
If my logic is off in anyway please let me know
I am somewhat thrown by your statements.
First you say "I know how to make an AXI4 peripheral in Vivado"
Next I read: "Should I make the peripheral a Master or Slave?"
Maybe I am wrong but to me it says you don't really know what you are doing.
Simplest is to:
Instance a zynq system.
Add the IP with the name "AXI GPIO". (Which, by the way, is an AXI slave.)
Run the auto connection.
Assign the right I/O pins to the GPIO port. (check your development system manual)
Build the system.
By the way you find the address of the peripheral in the address tab and it normally is 0x0080000000.
You wrote that you made a server (TCP/IP). "All" it has to do is write the received value to a register in the GPIO block. (Here I assume Xilinx has a document which describes how the GPIO block works and has example GPIO drivers.)
I want to add external push button to Parallella's GPIO pins.
Is it correct to connect push button just like the users did for Raspberry pi boards?
enter image description here
if it's working, what resistor should I use? and if it's not correct, what schematic should I follow to connect push-button to one of the GPIOs?
I just had a quick look at the Parallella schematic. It is 17 pages with rather a lot of connections so I can't do a full analysis in a few minutes. (I would also need to work through the datasheet)
You must check which voltage your I/O pin is operating at. If it is 3V3 you can use the schematic as-is. If it is a different voltage you have to replace the 3V3
with whatever the I/O voltage is. For the rest the principle is OK: Pull the port low with a resistor and use a push button to the selected voltage to make it active high.
If you don't know which voltage to use set the pin in output mode and output a 'high' Then measure which voltage appears.
Note that in general it is safer way to use a resistor (e.g. 50KOhm) to tie the pin to the I/O voltage. Then use a push button to pull the pin low. If you make a mistake, the pin is more likely to survive as the resistor limits the current.
On the raspberry pi 3 all GPIO pins are powered up with a direction of "input". Each pin has a pull-up and a pull-down resistor associated with it. The status of these resistors is preserved through power loss or reset. (This is why there is no way to read the status of these resistors because they may not be known after a reset.)
I wrote a program that forces all the pull resistors to disabled so that nothing is pulling the lines high or low and then rebooted. /sys/class/gpio/*/direction and values all indicate success.
After reset, all pins came up in the input direction and without pull resistors enabled except for:
GPIO2: pulled-up (No problem, due to externally soldered i2c pull-up
resistor)
GPIO3: pulled-up (No problem, due to externally soldered i2c pull-up resistor)
GPIO14: (TXD0) pull-down resistor has been re-enabled somehow!
GPIO15: (RXD0) pull-up resistor has been re-enabled somehow!
I have already previously used raspi-config to disable both the serial console logging and the serial uart. So I would think nothing in the boot process should alter the peripheral registers controlling GPIO14 and GPIO15.
What in the boot process is reconfiguring the GPIO15(RXD0) and GPIO14(TXD0) pins to have their pull-up/down resistors enabled and how to I stop it?
One thing I found out:
The pull-up/down resistor configurations on the broadcom chipset are non-volatile. (This is actually why you can't query what their status is in anyway; because the chip doesn't know what they are from boot time and can't query them itself. The CPU can only set them.)
So, if you turn off all the pull-up/down resistors the raspian distribution boots with all pins in the output/high-z configuration except for GPIO2 and 3 because these are the I2C pins with physical pull-up resistors soldered on board. The Tx GPIO pin also reads high but I think it due to the bluetooth system being initialized in the kernel and I don't know how to disable that.
So if you set all the pins to input/hi-z and disable pull-up/pull-down it will come up that way after reboot (unless you've enable something in the kernel or otherwise changed them after power-up)