Does SPI subsystem is implemented by spi.c and spidev.c is protocol driver and I have read few mentions that we just need to mention spidev in device tree to use this, but how spidev does device specific operation i.e transfers?(it has to know about specific details of spi registers etc. this is where SPI controller driver comes but how these two are linked).Please correct me if I mentioned anything wrong.
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i need some help.
i built custom board and had problem with my adc reading, it's not software problem...yet.
my question is really hardware. it might be my lack of understanding from reading STM32f407 manual book. so i have my microcontroller STM32f407zgt6 with LQFP144 package. and i fail to read the ADC. i use stm32cubeide for programming but my programming is very simple since i follow this link https://deepbluembedded.com/stm32-light-sensor-ldr-interfacing-ambient-light-sensor-project/. my question is:
do i have to connect pin VREF+ to VDDA externally to activate the ADC?
cause in STM32f103 with LQFP48. the VREF+ pin doesn't exist and the manual says that it's internally connected to VDDA pin. can i assume that the same rules can be applied to STM32f407ZGT6? or the external connection of VREF+ -> VDDA is mandatory since it is using LQFP144 package? cause i didn't connect it in my custom board and left the VREF+ pin hanging.
i just wanna use the ADC VREF+ = VDDA in LQFP144, so i assume that it is internally connected, is my assumption wrong?
here is my confusion on STM32F4 manual:
and
please help. i might have a false design on my custom board then...
In the smaller packages Vref is connected internaly just to save external pins.
In the larger packages Vref can be connected to a different power rail - more stable or slightly different, like 3.0V. And there is no configuration options to connect Vref to Vdda. The datasheed states explicitly in the "General operation conditions" chapter:
And in most cases, Vref is just wired to Vdda.
I am wishing to use the Sync FIFO interface of a FT232H on a custom board from python on a RaspberryPi. I would use PyFTDI, but PyFTDI doesn't implement the Sync FIFO interface mode. The constant for the Sync FIFO mode is defined in PyFTDI but never used. I plan on accessing Sync FIFO by using PyUSB directly with PyFTDI as a reference. However as PyFTDI doesn't ever use the Sync FIFO mode, I don't know what FTDI commands are used for the mode on the USB endpoints. The documentation I have been able to find from FTDI tell how to use the proprietary library as opposed to the low level command structure actually sent to the chip. I have done a bit of searching, but FTDI provides many documents and it is a bit of information overload.
Does anyone know where the documentation is which covers the low level command codes and arguments which are sent to the FTDI USB end points? I am assuming the authors of PyFTDI were referencing something besides wire sniffing.
According to their knowledge base FTDI provides an API document under an NDA for some circumstances.
In some circumstances, it may be desirable to develop a custom driver for an exotic operating system or an embedded system. In these circumstances, an API document may be obtained from FTDI under NDA to allow driver development for FTDI devices. To request a copy of the API document, please contact FTDI Support support1#ftdichip.com.
I have a 1.5 OLED SSD1309 display with ZIF connector. Based on a interfacing scheme from the seller I made a scheme that should connect this display with STM32 based MCU via i2c. Interfacing scheme is based on AT MCU, so I wonder can this apply to any type of MCU?
Here is the link I used as a reference: https://www.buydisplay.com/download/interfacing/ER-OLED015-2_Interfacing.pdf (I also don't understand this VCC +12.5V, do I have to make add 3V to 12.5V regulator based circuit as well?)
I also found this: https://github.com/afiskon/stm32-ssd1306
It says that this library is working with SSD1309 as well, so I would use it for this if all this above make sense and can work.
Does someone have experience with this type of connecting OLED displays with MCU, because almost all I could find are already soldered boards with display on it.
Is it possible to access external hardware without using a driver, i.e. not having the driver abstraction layer in between program and external device?
Can you use a device by implementing your own driver-like controlling/handling directly in your program code?
I'm trying to understand a program that implements a Modbus protocol and some very specific Modbus configurations. Now I don't know how exactly it communicates with the Modbus devices.
It looks to me that this is very similar to what a driver does.
But can it even communicate DIRECTLY with the device without having a driver installed?
Yes, there are several micro-kernel OS's that always configure this way -- drivers are entirely implemented outside of the kernel.
The first thing you likely need is to get access to the device's registers; typically performed with mmap(), you may need to dig around a bit to find the right settings for cacheability, etc...
Second problem is interrupts. Unless you are running something like QNX, you won't have a way to have interrupts signal your program directly. You will probably have to turn them off and poll the device periodically.
If you are using linux and need io ports (inb, outb, etc...) man ioperm for more information.
I'm working with board support package (BSP) in VxWorks that uses pciAutoConfig() to configure the PCI bus. When I add an Ethernet controller card to the bus the pci display routines do not show the card.
Using a bus analyzer I discovered that the Ethernet adapter actually consists of a PCI-to-PCI bridge with two Ethernet controllers behind the bridge. It appears that the BSP is not properly dealing with the PCI-to-PCI bridge that the Ethernet controller contains.
My question is, what library and configurations should I look at to configure the PCI-to-PCI bridge? I'm thinking these calls will go in sysHwInit(), where the existing pciAutoConfig() calls are.
pciAutoCfgCtl() has a PCI_BRIDGE_PRE_CONFIG_FUNC_SET parameter that points to a user defined function to configure the bus. Is this the only method? Or is there something in the VxWorks libraries that can do this for me?
I think looking at the BSP-specific PCI auto-configuration routines is the way to go.
Is the PCI-to-PCI bridge on your network card being enumerated properly? Do the primary and secondary windows make sense? Is there enough overall PCI memory space to include the space required for the secondary bus on which the Ethernet controller chips are located? If not you may need to increase the PCI_MEMIO32_SIZE_SET value.
If the enumeration of the bridge on the adapter card is not correct you should be able to manually configure the bridge by adding code to the BSP's sysPciAutoconfigPreEnumBridgeInit() routine.
Does the BSP provide a sysPciAutoconfigInclude() routine which will enumerate the Ethernet controller devices on the network adapter by default? If not you will have to add the Ethernet controller devices to it otherwise they will be ignored during the enumeration cycle.