Can a device connected to main processor can initiate a i2c communication.
For example, FAN connected using i2c bus, is it possible for a FAN to send a feedback to main processor.
Common solution to a problem like this is to have a separate interrupt line.
I3C supports in-band interrupts, if you're not set on I2C yet.
Related
I want to send data through USB between STM32 and Raspberry Pi. I don't want to use USB to Serial convertor, but instead have a actual USB Connection (maybe CDC class). I have to send data at high rate (Full speed). Please guide on how to achieve this?
A USB-serial connector is simply a microcontroller implementing a USB CDC/ACM virtual COM port and bridging to a UART which you would connect to a microcontroller's UART interface.
In your case you can simply implement the CDC/ACM directly on the STM32 using either of its USB device controller peripherals (USB support varies depending on the specific device https://www.st.com/resource/en/application_note/dm00296349-usb-hardware-and-pcb-guidelines-using-stm32-mcus-stmicroelectronics.pdf).
How you actually implement that will depend on what specific part, and what library or framework ecosystem you are using (e.g. SPL, CubeMX, Mbed). There are reference implementations, examples, drivers and libraries for all of these.
Your milage may vary, but I have measured ST's own USB library and example CDC/ACM virtual COM for STM32F1xx on a 72MHz MCU achieving 700kbits/s. Note that the performance is independent of the baud rate you might set on the host when you open the he VCP. Setting the baud rate simply sends a control packet to the device that can be used to set the baud rate of a UART in bridging applications. In your case such control packets can be ignored. There are similar packets for modem control signals such as DTR, RTS, CTS and RI, which you might choose to us for flow control or other signalling.
I am trying to build a small battery monitoring system using LTC 6804-1 IC which will send the cell voltages over I2C to my STM32 Nucleo board. I have read and understood I2C and how to use the HAL APIs for communication. However, I am not able to understand anything about the communication from the datasheet of LTC 6804-1. https://www.analog.com/media/en/technical-documentation/data-sheets/680412fc.pdf I was looking for the slave address it sends data to and also the length of data. But I can see configuring some data registers which is bit of confusing. At point I do not know where to even start? Or is it actually easy that I have to connect wires and it starts?
Any help would be highly appreciated. Thanks!
The LTC6804 is not using I2C for communication, it's using SPI. It can host I2C communication to a slave device. Reread the data sheet thoroughly. Although I must agree, the manual is not really written very well, or at least there could be a lot more info, not only on how to get started...
I am using STM32H7 family of microcontroller as SPI Master Transmit device which needs to talk to 4 SPI slave devices receive only which are also all STM32H7 MCU's. Both master and slave are configured for software slave management.
The confusion is how slave will identify when master wants to talk to it or transmit data to it without using hardware NSS pin?
How slave device will start receiving in this scenario and stop receiving when all data transmitted?
If you use software slave select (NSS), you must select and deselect the SPI interface by software.
Typically, you would setup an external interrupt on the pin used as NSS/CS and select/deselect the SPI interface when the interrupt is triggered.
On an STM32F1 chip, the SPI interface is selected/deselected by setting/clearing the SSI bit in the SPI_CR1 register. I assume it's very similar on a STM32H7 chip.
Update
I've just checked the STM32H7 and it's exactly the same.
It is very simple. Every slave has one pin called CS. You need to select this device by setting this pin just by using the GPIO. Then you can transmit or receive data. Remember that master has to supply clock even if it wants only to receive data.
It seems that the code shown below can manage the problem.
__HAL_SPI_ENABLE(&hspi1);
__HAL_SPI_DISABLE(&hspi1);
I am porting an I2C driver to Linux-4. This device provides multiple I2C addresses for different function simultaneously.
For example:
address 0xAA is for access of SPI flash.
address 0xA0 is for access of EEPROM.
address 0x60 is for normal access (control purpose).
Is it possible to support access of different I2C address in single-one I2C device driver?
Any help appreciated,
Thanks
I think it is possible. Using i2c_transfer() you are giving particular address in i2c_msg structure of the device you want to communicate with. So your driver will be able to communicate with all of the functions of your i2c device.
Depends on what type of I2C driver you are talking about, bus(adapter) or chip(client) driver?
i2c-dev.c is a kind of bus driver with character device interface which exports kernel low level I2C API to userspace.
For each registered I2C adapter Kernel will add i2c-N device node in /devuserspace interface.
But you can't read/write EEPROM chip attached to /dev/i2c-N like simple character device or file. You need to write some utility program regarding chip protocol.
But in Linux there is are special EEPROM chip drivers like eeprom.c or at24.c for registering I2C EEPROM devices with addresses of 0x50..0x57(if I'm not wrong) to Kernel and creating files in /sys userspace interface.
You can access them as a file in:/sys/bus/i2c/devices/0-005x/eeprom
Thanks for Dražen Grašovec and user2699113 's help.
I am porting a I2C device driver (chip, client) to Linux-4.9.
This chip accepts different I2C device address for different purpose.
My goal is to create only one I2C device on Linux device tree file (.dts)
I resolved my issue by using i2c_new_dummy().
In driver probe function,
I made two i2c_new_dummy() to create two additional i2c clients.
One(client#1) is for accessing of I2C address 0xAA, another(client#2) is for I2C address 0xA0.
So I can use client#1 to communicate with its SPI flash and use client#2 to access it EEPROM.
I am developing a prototype for adaptive cruise control using two raspberry pi's. I have tested SPI on pi and it works (checked it through loopback). Now i want to write this data to the cotroller. So, after referring to resources i found Socketcan should be used in order to interface can controller with the pi. So i request some one to explain how the communication happens like
1. After writing to spi how the can controller can take that data?
2. If socketcan be used to take data from spi , i need to know how?
Thanks