Using a STM32G0F06
I have a bootloader/application that I am debugging. I am facing a strange problem. Often, I command the app to drop to bootloader (via a software reset). When I execute the software reset code, occasionally the core locks up.
Here is a video showing the core registers and the disassembly as I step debug through the reset code:
https://youtu.be/8SxjNWpSIss
A couple of questions:
Is this a MCU core lockup? If not, what is it? Does the PC go to 0x1FFF19A6 during a core lockup, or is that just random?
How come the IWDG I have configured does not reset the MCU after it has locked up?
Does it get locked up to? Is there some way I can programmatically recover from a core lockup: MCU pulls its' own external reset pin low?
If the PC has the value 0x1F... I suspect that it is not locked up but running the internal boot ROM. The boot ROM will either kick the watchdog itself or maybe turn it off, so that is why you can't rely on the watchdog to get out of it. ST probably don't want you to debug the ROM, so maybe that is responsible for your further problems.
See AN2606 for how to make sure you don't go into the boot ROM after you reset.
Related
I have MCU STM32F415xx and was trying to write on internal flash. But for reason I don't know PGPERR and PSGERR flags were turning on in random time (as I found, problem can be found anywhere in HAL libraries) and HAL functions were stopping. I turned out flags checkout in FLASH_WaitForLastOperation. And after that MCU is not responding on any try to connect. Reference manual says, that if this flags are on, flash operations just will not be performed, but my MCU is not working and I cannot connect to it with ST-LINK Utility (and Programmer as well) even with reset pin. So what could happen and is there any way to reanimate my MCU?
My question is, if I manage to develop some kind of bootloader and flash it (is it called that when you put a bootloader on an MCU?), and it works horribly, can it brick the MCU entirely, making it completely unusable, permanently?
The reason I'm asking is that I've been tasked to develop a bootloader for the STM32F407. Problem is, I don't know anything about bootloaders or anything of the sort, which means that I have a lot to learn.
I appreciate any answers, thank you!
In short no you cannot brick a microcontroller with a bootloader.
In the end bootloader is just a firmware and can be erased away using the programmer via SWD
Erase the flash and your controller is as good as new
In general, absolutely, I have a collection of bricked microcontrollers, every so often I get lazy and there goes another.
It is very specific to your microcontroller and family. For example, pin count is very important, as much bang for your buck as you can get, if your microcontroller relies on certain pins for in circuit (or even in a programming fixture) and those pins can be repurposed by software. For example jtag pins that can also be gpio pins. And your code for some reason uses them as gpio pins, AND the design of the chip is such that they cannot use the jtag interface when the chip is in reset, then you can get bricked.
Another very easy one is the pll or clocks in general. If/as you develop code to initialize the clock system (assuming you choose to do that, even if you use chip vendor supplied code) and you have a bug that switches the chip over to a clock that you have not properly initialized or isnt there, it might brick.
Now some chip designs, many, help you out in various ways. The AVR family in general there is a programming mode that happens while the chip is in reset or is related to reset such that whatever code is in flash cannot affect its functionality, you can have a bad board design, sure, but your code cannot prevent it from working. Another method is a "strap" a pin (or pins) that is dedicated to a boot function, set one way normal boot, tie it the other and it goes into an alternate bootloader. This is what you have on the stm32 boot0 and sometimes boot1 depending. that is your get out of jail free card for that chip family, if you brick your chip (pll/clock or mess up the SWD pins by using them as gpio), you "simply" change boot0 and it boots into an internal bootloader (which AFAIK you cant mess up) which is known to work. From that bootloader you can use SWD (chips not bricked now) or the bootloader itself (always serial, sometimes usb or other is supported). NXP similar deal. Atmel ARMs used to have (do have) SAM-BA now they really only support SWD, you can get some samba code and try to lock it into the flash, but way too easy to unlock and or trash that flash, so that is a fail on their part.
As part of your system design if you dont have one of these built into save you from bricking features (like boot0 on an STM32), then I recommend you add one. Very early code initializes a dedicated gpio pin as a strap into your software, if that gpio pin is pulled one way do a normal boot, if pulled the other then spin in an infinite loop or jump to some other guaranteed to not be buggy code. Not a complete guarantee that you wont build the project wrong and trash this code, but it at least allows you to develop your bootloader/project and not brick a tray full of parts/boards as you work through the peripherals that can brick it.
Note letting smoke out of the part is another way to brick it as well, and that can/does happen from time to time as well.
Lots of examples on how to boot an STM32, plus various code from ST that you can use as a starting point as well. (all of which is of various quality, you get what you pay for). Their docs are good, better than some of the competition, not difficult at all to boot and configure their peripherals, sometimes easier than trying to use a canned library. YMMV, you should try various solutions. But if you are new to this, bricking is highly likely, fortunately you have a chip that you cant brick so long as your board design breaks out the boot0 pin. For a prototype board for an STM32 I prefer to have a boot0 button and a reset button, just reset resets the chip and runs, hold boot0 and press reset and it goes into the bootloader. both have to be wired in properly with the right pull up or down as needed for this task. or a jumper works tie boot0 directly high or low then pop reset, costs you more time, but works.
Yes You can brick the Micro controller to never recovered state. I did this and i did it in STM32F427.
Bootloader is all about carefully selecting Clocks, Peripharals and Interrupts priority. if you do this, there are less chances to brick the controller. Also test everything before release your code as some companies wants to save proprietary information to be saved so they blow up the JTAG lines, the only way to program is via Bootloader and if it is not perfect, voila, you just bricked the controller.
I just started working on a STM32L151 microcontroller. I've setup the debugger to break at first instruction (not main), but when I start debugging the program counter stops at 0x1ff00b84 which isn't even a part of the flash (starting at 0x8000000 -> 0x8010000).
It gets wierd, because when i try resetting the debugging session (without downloading the program again), a couple of times it finally stops at the first instruction in my startup-file (startup_stm32l1xx_md.s) and everything runs smoothly until the next time I need the program the device and start the debugger again.
I use CoIDE with the compiler "GNU Tools ARM Embedded 4.8 2014q2".
And I run on some custom HW that just arrived. I use SWD from a STM32 Discovery Board to program the chip with.
Hope someone has an idea?
That address is in the bootloader ROM. This behavior suggests that the BOOT0 pin may be floating; make sure that it is tied to GND to boot from flash.
I have these related questions:
Does anybody know how an OS gets to know all hardware connected on the motherboard? (I guess this is called "Hardware Enumeration").
How does it determine what kind of hardware is residing at an specific IO address (i.e.: serial or parallel or whatever controller)?
How to code a system module which will do this job? (Assuming no OS loaded yet, just BIOS).
I know BIOS is just a validation and an user friendly interface to configure hardware at boot time with no real use after that for most modern OS's (win, Linux, etc). Besides I know that for the BIOS it should not be difficult to find all hardware because it is specifically tuned by the board manufacturer (who knows everything about it!). But for an OS or an application above BIOS that is a complete different story. Right?
Pre-PCI this was much more difficult, you needed a trick for each product, and even with that it was difficult to figure everything out. With usb and pci you can scan the busses to find a vendor and product id, from that you go into a product specific discovery (like the old days this can be difficult). Sometimes the details for that board are protected by NDA or worse you just dont get to know unless you work there on the right team.
The general approach is either based on detection (usb, pcie, etc vendor/product ids) you load a driver or write a driver for that family of product based on the documentation for that family of product. Since you mentioned BIOS, win, linux that implies X86 or a PC, and that pretty much covers the autodetectable. Beyond that you rely on the user who knows what hardware was installed in the system and a driver that came with it. or in some way you ask them what is installed (the specific printer at the end of a cable or out on the network if not auto detectable is an easy to understand example).
In short you take decades of experience in trying to succeed at this and apply it, and still fail from time to time since you are not in 100% control of all the hardware in the system, there are hundreds of vendors out there each doing their own thing.
BIOS enumerates the pci(e) for an x86 pc, for other platforms the OS might do it. The enumeration includes allocating address space for the device based on pci compliant rules. but within that address space you have to know how to program that specific board from vendor documentation if available.
Sorry my English is not very good.
Responding questions 1 and 2:
During the boot process, only the hardware modules strictly necessary to find and start the OS are loaded.
These hardware modules are: motherboard, hard drive, RAM, graphics card, keyboard, mouse, screen (that is detected by the graphics card), network card, CD / DVD, and a few extra peripherals such as USB units.
Each hardware module you connect to a computer has a controller that is like a small BIOS with all the information of the stored device: manufacturer, device type, protocols, etc
The detection process is very simple: the BIOS has hardcoded all the information about the motherboard, with all communication ports. At startup, the BIOS sends a signal to all system ports asking the questions "Who are you? What are you? How do you function?" and all attached devices answers by sending their information. In this way the computer knows how much RAM you have, if there is present a keyboard or a mouse, which storage devices are available, screen resolution, etc ...
Obviously, this process only works with the basic modules needed to boot the system, and does not work with complex peripherals that require specific drivers: printers, scanners, webcams ... all these complex peripherals are loaded by software once the OS has been charged.
Responding question 3:
If you wants to load a specific module during the boot, you must:
- Create a controller for this module.
- If the peripheral is too complex to load everything from the controller, you must to write all the proccess to control that module directly in the BIOS module, or reprogram the IPL to manage that specific module.
I hope I've helped
Actually, when you turn on your system, the BIOS starts the IPL (Initial program load) from ROM. For check the all connected devices are working good and also check the mandatory devices such as keyboard, CMOS, Hard disk and so on. If it is not success, it gives an error flag to the BIOS. The BIOS shows us the error through video devices.
If it is success, the control of boot is transferred to BIOS for further process.
The above all process are called POST (Power On Self Test).
Now the BIOS have the control. It checks all secondary memory devices for boot loader of the OS. If it hit, the bootloader's memory address is transferred to RAM.
The Ram started to execute the bootloader. Here only the os starts to run.
If the bootloader not hit, the bios shows us the boot failure error.
I hope your doubt clarified...
What is the best way to COMPLETELY restart the iOS Bluetooth BTLE central and peripheral managers, after communication stops between two iOS devices (iPad-mini)?
Sometimes after a few minutes, my BTLE communication stops (central can not get response from peripheral, though debug output of each device shows app still running and central app still is trying to scan peripheral, and peripheral is still advertising), and will not start again:
after stopping scanning and stopping advertising, comm still doesn't work;
after re-opening the app, comm still doesn't work(!);
after POWER CYCLING the iPads comm works again, but then after a few minutes dies.
Therefore, something I'm doing is clobbering maybe the iOS core Bluetooth software.
Sometimes there are error messages from the underlying BTLE layer.
BACKGROUND:
Each iPad in this system alternately works as central, to read/write data to others, and then as peripheral, to be read by others. Never at the same time, and with a 1 second delay between transistions.
The bluetooth stack is not the most robust part of iOS. This may have improved in iOS7 but issues have always existed. You most probably are stressing the system so that this hang happens more often. You should create a bug report and send it to Apple. Or create a TSI, as a developer you have two of those every year. They are the only ones who can do something about it.
To solve the issue, restarting the app usually helps but sometimes bluetooth needs to be turned on/off or worst case the device needs to be power cycled. Unfortunately, there is not programmatic way to do any of these.