Intro
I wanna give a last chance to this board before put it in a trash haha :). Right now I prefer use standard motherboards, Ubuntu server, automatic main power switch and perif. to have something reliable over the time though.
Raspberry Pi wanted configuration
-wanna use Rasbian 11.
-no boot from external hdrive.
-will mount external hdrive using the UUID for the data
My questions
1 - Enable overlay and readOnly mode (in raspi-config) doesn't seem good enough- With this method rootfs parition in fstab is not 'ro'. So what?
2 - Is it more reliable to have the both partiton in readOnly (boot and rootfs) ?
3 - What about the log, temp, ram,...? Is there anything else to think about? What would be the complete list with a bit of explanation?
Thank you!
I have try to edit fstab, and add 'ro' to the rootfs partition but doesn't keep after a reboot.
Related
I am writing an external bootloader for the STM32F730Z8 - (why? I need one windows code that can run the bootloader for the STM32, or use the STM32 to reprog a connected ATF1508 for my client). I've done this before, using info in AN3155 and AN2606. On lesser CPUs, this has had no difficulty (i.e. STM32L4P5). In this case, I try the same:
1-cycle \RESET & BOOT0 to boot to supervisor mode
2-autobaud successfully
3-send 0x00 to get the list of commands, successfully
4-send 01 to get the version and protection, successfully (vers 49, rp and nt both 0)
5-send 02 to get chip id (0x0452), successfully
6-send 0x73 to write-unprotect flash, successfully (i.e. receive back two ACK)
7-send 0x44 to begin an extended erase (intending only to erase sector 0).
This is where it fails. I get neither ACK nor NACK - it just times out. I don't even get to the second half of the extended-erase command where I send it the sector info. (On the STM32L4P5 it succeeds here easily and goes on to finish erasing, then to write code successfully.)
I've tried very long waits & repeat loops to wait for the ACK (many minutes). From past experience this should be fast, it is only the second stage where I tell it how much flash to erase that takes any significant time.
I've inspected the protection option areas of memory, at 0x1FFF0010, 0018, and they are unprotected, as per factory defaults.
I'm communicating over an FT231XS-R, using the D2XX driver calls. I can mess with the baud rates and such, but that only prevents it from autobauding...and we're doing that fine (9600/8/1/E). I've played with the D2XX SetTimeouts - if set too hasty that only screws up earlier commands. I'm wired to a 20 MHz crystal, and the application runs at 200 MHz, but my understanding is that the bootloader just runs at the internal RC clock rate.
I'm certainly missing something stupid, but I didn't see it in the documentation. Help?
Jeff Casey / Rockfield Research Inc. / Las Vegas, NV
Fixed, disregard.
The fineprint of AN3155 clued me in. On the description of the Write Unprotect command, it says that a system reset will be performed after completion. How did I miss this on the STM32L4P5? I just didn't read it. But why did it work then? In the really fine print next page, in a footnote to the flowchart, it says that they were just foolin'....system reset is only called for some (..list omitted..) and for other STM32 products no system reset is called for.
My earlier success had the following sequence:
reboot-supervisor
autobaud
get
gvrp
gid
wpun
xerase
wpun
write
verify
reboot-user
obviously that doesn't work for the F730. what works is:
reboot-super
autobaud
get
gvrp
gid
wpun
reboot-super
autobaud
get gvrp
gid
xerase
reboot-super
autobaud
get
gvrp
gid
write
verify
reboot-user
(obviously I can skip a few of the repeated steps, like get-id, but basically it needed a reboot and re-autobaud.)
note that i had to reboot-super a 3rd time...this was because the write attempt timed out after the xerase unless i went through the whole sequence again. funny, though, the spec doesn't say anything about resetting after an erase. i cross posted this question on the STM32 community site, and I'll do the same with this answer and ping them on this.
Thanks for reading, cheers. Jeff
I am writing an operating system for the raspberry pi.
I have a problem with the sdcard driver for the custom sdhost controller (emmc2)
of the raspberry-pi 4 (Cortex-A72, ARMv8-A, bcm2711 chipset).
Without using sdma everything works. With sdma, read works, but after writing sectors, the data on the sdcard sometimes contains invalid data.
For the sdma data transfer, I use a transfer buffer with a device type memory attribute (nGnRnE). When I use a fresh data buffer for the dma write transfer, the data on the sdcard is correct. But when I reuse the same buffer for the next write, then the sector on the sdcard partially contains data from the previous buffer content.
Maybe this is a cache coherency problem. I have enabled all caches (I and D). In the ARM manuals there is a talk of the SCU (snoop control unit) and I don't know whether I have do bother about the SCU.
My questions are:
Is it necessary to enable the SCU on a Cortex-A72 and how can this be done ?
What other things have to be kept in mind when using dma for device access ?
I found the solution for my problem:
On the raspberry pi 4 (bcm2711 chip), the physical addresses that are written into the registers of a dma engine must be legacy master addresses. The legacy master addresses are in the range 0xC0000000-0xFFFFFFFF. So I have to add 0xC0000000 to the values of the physical addresses that are written into the registers of the sdhci controller.
The documentation can be found here:
https://datasheets.raspberrypi.org/bcm2711/bcm2711-peripherals.pdf
1.2. Address map
1.2.4. Legacy master addresses
The answer to the other SCU question is: it is not necessary to enable the SCU on the Raspberry Pi 4 when the caches are enabled.
I'm just creating an app(kivy) for a raspberry pi(3b) with 7 inch touchdisplay. In addition I implemented a light sensor (TSL2591), which can regulate the brightness of the backlight using following command:
os.system('sudo sh -c "echo '+str(brightness)+' > /sys/class/backlight/rpi_backlight/brightness"')
with values of brightness 0 to 255
Works fine so far, but I do update the brightness once a second. If I'm not wrong, the command overwrites a config file and I mind of write access to the SD Card that often. I think the SD card will be corrupt after a short period of time.
For sure I can try to get less write operations, but it also leads to less smoothness:
update slower than 1 sec
only write if brightness value really changes
don't use all of the 255 steps
So the main question is: is there any other way to control the brightness? Or any workaround? I could not find a "real" Datasheet or any other advice on the internet. So maybe there is another way.
That's not a conventional disk file; it's a "device special file" which the kernel artificially creates to look like a disk file. It allows you to "talk" to device drivers using standard read() and write() calls.
You need not worry about SD card wear.
previously thank you for read my Question.
I'm implementing 'SMP' work on my hypervisor project.
What i want to do is like bellow.
One virtual machine have two vcpus. And this Virtual Machine is working on 2 pCPU.
For example, one linux has 2 cpu as SMP.
Firstly, what i tried is set pc value as 0x80500000.
(zIamge is on 0x80500000 address)
when both pcpu run, pcpu0 works fine. but pcpu1 got a error like bellow.
It means 'prefetch abort' from Virtual Machine. and it's occurred when access level 3 as iss indicate 'f'.
I don't know how to access this problem to solve.
If you need any specific information, please tell me. i will add more information.
Please tell me any tips and check point to solve this.
Lastly, thank you.!!
I'm very new to WebIOPi and I'm trying my first tests. First of all I apologize for my english.
I'm trying to get to work a RPi with a MCP3008 on CE0 and a MCP23S17 on CE1 with SPI bus.
My problem is that devices only work when connected on CE1 (so, when 23017 is on CE0 I am not able to set pins to be inputs or outputs and to set it on 1 or 0, but 3008 is on CE1 and I see its levels changing. When - vice versa - 23017 is on CE1 it is fully functional, but 3008 outputs stay still).
Due to this, I think it is not an hardware issue (I don't have much expertise in electronics, but luckily I don't build my circuits by myself :) ), I think it is a problem in WebIOPi config. Here is my WebIOPi config:
[DEVICES]
mcp1 = MCP23S17 chip:1 slave:0x27
adc0 = MCP3008 chip:0
I only added these two lines to my config file.
I did not touch anything else of my original WebIOPi installation.
In this case (adc0 fully functional, mcp1 not working), when loading the WebIOPi devices monitor I see adc0 levels working good and mcp1 pins randomly changing between being a input and an output and from 0 and 1.
May it be a config error?
Use python and spidev module instead! Look my answer on another thread for function for the mcp3008 chip.