I am writing a model for a serial flash device. I wonder how do I best model the internal memory? I would like the memory size to be configurable by the user since I intend to reuse this model for different serial flashes. It also needs to retain its content upon reset while the rest of the logic is reset.
I tried using a statically allocated character buffer but that is not configurable and seems very inappropriate for such large sizes as my flash model. My flash model is 512 MB.
saved char flash_image[512 * 1024 * 1024];
Assuming this will go into Simics, it is best modeled with two subobjects, both of which are available in Simics Base.
The first is an image which stores the actual data, the second is a ram which is used to read/write into the image.
Both the image and the ram are connects using the init_as_subobj template which makes Simics automatically create them as sub-objects of the device.
They are placed in a group where we can add an init method, which sets default values for the required attributes of the subobjects; in this case the "size" of the image and the "image" of the ram.
The ram object also uses the map_target template, which gives us useful methods for reading and writing into the ram.
dml 1.4;
device sample_dev;
import "utility.dml";
import "simics/simulator-api.dml";
group flash is init {
param size = 0x1000;
method init() {
SIM_set_attribute_default(
ram.obj, "image", SIM_make_attr_object(image.obj));
SIM_set_attribute_default(
image.obj, "size", SIM_make_attr_uint64(size));
}
connect image is init_as_subobj {
param classname = "image";
}
connect ram is (init_as_subobj, map_target) {
param classname = "ram";
}
}
method write_test() {
try
flash.ram.write(0, 1, 42);
catch
log error: "write failed, it shouldn't!";
}
The size of the image is given a default value by a parameter in this example, but it can also be set or overridden by the user when creating the object, by assigning to the attribute flash.image.size, e.g. like this:
SIM_create_object("sample_dev", "dev", **{"flash.image.size": 0x2000})
Related
I would like to ask the following a question: im using stm32g0xx microcontroller and i want to change the flash address in linker script automatically and not be forced to changed manually every time i want to generate an apllication image to let it run from diffrent address. what im doing i wrote an application and i wrote it to tow different address"0x08001000 and 0x08004800" to have the apility to switch to other application incase one of them is updated or damaged. it worked fine but i need by every image to change the flash address manually and i would like to ask if it is possible to changed somewhere else out of the linker script like startup.s?
MEMORY
{
RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 8K
FLASH (rx) : ORIGIN = 0x8001000, LENGTH = 32K
}
MEMORY
{
RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 8K
FLASH (rx) : ORIGIN = 0x8004800, LENGTH = 32K
}
You can create two linker files and compile two times, each time with a different linker script and a different output binary. You will obtain the two necessary binaries. To integrate it on your project, it depends on your way of working (STM IDE, standalone Makefile...) which you did not mention.
As a side note, you should modify the LENGTH on your linker scripts, it will prevent the linker to place data where you have another application.
Your first application starts at 4KB (0x1000), and the second start at 18KB (0x4800), the lenght of the first application should be 18-4 = 16KB and the second LENGTH should be 32-18 = 14KB (if the FLASH total size is 32KB).
You can write two different linker script and apply one or the other in your building enviroment (with the -T linker flag) or you can use a variable for your ORIGIN and pass it with -Wl,--defsym=<VAR_NAME>=<VAR_VALUE>
I'm working on project on STM32L152RCT6, where i have to build a mechanism to self update the code from the newly gated file(HEX file).
For that i have implemented such mechanism like boot loader where it checks for the new firmware if there it it has to cross verify and if found valid it has to store on "Application location".
I'm taking following steps.
Boot loader address = 0x08000000
Application address = 0x08008000
Somewhere on specified location it has to check for new file through Boot loader program.
If found valid it has to be copy all the HEX on location(as per the guide).
Than running the application code through jump on that location.
Now problem comes from step 5, all the above steps I've done even storing of data has been done properly(verify in STM32 utility), but when i'm jump to the application code it won't work.
Is there i have to cross check or something i'm missing?
Unlike other ARM controllers that directly jump to address 0 at reset, the Cortex-M series takes the start address from a vector table. If the program is loaded directly (without a bootloader), the vector table is at the start of the binary (loaded or mapped to address 0). First entry at offset 0 is the initial value of the stack pointer, second entry at address 4 is called the reset vector, it contains the address of the first instruction to be executed.
Programs loaded with a bootloader usually preserve this arrangement, and put the vector table at the start of the binary, 0x08008000 in your case. Then the reset vector would be at 0x08008004. But it's your application, you should check where did you put your vector table. Hint: look at the .map file generated by the linker to be sure. If it's indeed at 0x08008000, then you can transfer control to the application reset vector so:
void (*app)(void); // declare a pointer to a function
app = *(void (**)(void))0x08008004; // see below
app(); // invoke the function through the pointer
The complicated cast in the second line converts the physical address to a pointer to a pointer to a function, takes the value pointed to it, which is now a pointer to a function, and assigns it to app.
Then you should manage the switchover to the application vector table. You can do it either in the bootloader or in the application, or divide the steps between them.
Disable all interrupts and stop SysTick. Note that SysTick is not an interrupt, don't call NVIC_DisableIRQ() on it. I'd do this step in the bootloader, so it gets responsible to disable whatever it has enabled.
Assign the new vector table address to SCB->VTOR. Beware that the boilerplate SystemInit() function in system_stm32l1xx.c unconditionally changes SCB->VTOR back to the start of the flash, i.e. to 0x08000000, you should edit it to use the proper offset.
You can load the stack pointer value from the vector table too, but it's tricky to do it properly, and not really necessary, the application can just continue to use the stack that was set up in the bootloader. Just check it to make sure it's reasonable.
Have you changed the application according to the new falsh position?
For example the Vector Table has to be set correctl via
SCB->VTOR = ...
When your bootloader starts the app it has to configure everything back to the reset state as the application may relay on the default reset values. Espessially you need to:
Return values of all hardware registers to its reset values
Switch off all peripheral clocks (do not forget about the SysTick)
Disable all enabled interrupts
Return all clock domains to its reset values.
Set the vector table address
Load the stack pointer from the beginning of the APP vector table.
Call the APP entry point.(vertor table start + 4)
Your app has to be compiled and linked using the custom linker script where the FLASH start point is 0x8008000
for example:
FLASH (rx) : ORIGIN = 0x8000000 + 32K, LENGTH = 512K - 32K
SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET;
where FLASH_BASE's value must be equal to the address of your IROM's value in KEIL
example:
#define FLASH_BASE 0x08004000
Keil configuration
I'm using a STM32F401VCT6U "discovery" board, and I need to provide a way for the user to write addresses in memory at runtime.
I wrote what can be simplified to the following function:
uint8_t Write(uint32_t address, uint8_t* values, uint8_t count)
{
uint8_t index;
for (index = 0; index < count; ++index) {
if (IS_FLASH_ADDRESS(address+index)) {
/* flash write */
FLASH_Unlock();
if (FLASH_ProgramByte(address+index, values[index]) != FLASH_COMPLETE) {
return FLASH_ERROR;
}
FLASH_Lock();
} else {
/* ram write */
((uint8_t*)address)[index] = values[index]
}
}
return NO_ERROR;
}
In the above, address is the base address, values is a buffer of size at least count which contains the bytes to write to memory and count the number of bytes to write.
Now, my problem is the following: when the above function is called with a base address in flash and count=100, it works normally the first few times, writing the passed values buffer to flash. After those first few calls however, I cannot write just any value anymore: I can only reset bits in the values in flash, eg an attempt to write 0xFF to 0x7F will leave 0x7F in the flash, while writing 0xFE to 0x7F will leave 0x7E, and 0x00 to any value will be successful (but no other value will be writable to the address afterwards).
I can still write normally to other addresses in the flash by changing the base address, but again only a few times (two or three calls with count=100).
This behaviour suggests that the maximum write count of the flash has been reached, but I cannot imagine it can be so fast. I'd expect at the very least 10,000 writes before exhaustion.
So what am I doing wrong?
You have missunderstood how flash works - it is not for example as straight forward as writing EEPROM. The behaviour you are discribing is normal for flash.
To repeatidly write the same address of flash the whole sector must be first erased using FLASH_EraseSector. Generally any data that needs to preserved during this erase needs to be either buffered in RAM or in another flash sector.
If you are repeatidly writing a small block of data and are worried about flash burnout do to many erase write cycles you would want to write an interface to the flash where each write you move your data along the flash sector to unwriten flash, keeping track of its current offset from the start of sector. Only then when you run out of bytes in the sector would you need to erase and start again at start of sector.
ST's "right way" is detailed in AN3969: EEPROM emulation in STM32F40x/STM32F41x microcontrollers
This is more or less the process:
Reserve two Flash pages
Write the latest data to the next available location along with its 'EEPROM address'
When you run out of room on the first page, write all of the latest values to the second page and erase the first
Begin writing values where you left off on page 2
When you run out of room on page 2, repeat on page 1
This is insane, but I didn't come up with it.
I have a working and tested solution, but it is rather different from #Ricibob's answer, so I decided to make this an answer.
Since my user can write anywhere in select flash sector, my application cannot handle the responsability of erasing the sector when needed while buffering to RAM only the data that need to be preserved.
As a result, I transferred to my user the responsability of erasing the sector when a write to it doesn't work (this way, the user remains free to use another address in the sector to avoid too many write-erase cycles).
Solution
Basically, I expose a write(uint32_t startAddress, uint8_t count, uint8_t* values) function that has a WRITE_SUCCESSFUL return code and a CANNOT_WRITE_FLASH in case of failure.
I also provide my user with a getSector(uint32_t address) function that returns the id, start address and end address of the sector corresponding to the address passed as a parameter. This way, the user knows what range of address is affected by the erase operation.
Lastly, I expose an eraseSector(uint8_t sectorID) function that erase the flash sector whose id has been passed as a parameter.
Erase Policy
The policy for a failed write is different from #Ricibob's suggestion of "erase if the value in flash is different of FF", as it is documented in the Flash programming manual that a write will succeed as long as it is only bitreset (which matches the behavior I observed in the question):
Note: Successive write operations are possible without the need of an erase operation when
changing bits from ‘1’ to ‘0’.
Writing ‘1’ requires a Flash memory erase operation.
If an erase and a program operation are requested simultaneously, the erase operation is
performed first.
So I use the macro CAN_WRITE(a,b), where a is the original value in flash and b the desired value. The macro is defined as:
!(~a & b)
which works because:
the logical not (!) will transform 0 to true and everything else to false, so ~a & b must equal 0 for the macro to be true;
any bit at 1 in a is at 0 in ~a, so it will be 0 whatever its value in b is (you can transform a 1 in 1 or 0);
if a bit is 0 in a, then it is 1 in ~a, if b equals 1 then ~a & b != 0 and we cannot write, if bequals 0 it's OK (you can transform a 0 to 0 only, not to 1).
List of flash sector in STM32F4
Lastly and for future reference (as it is not that easy to find), the list of sectors of flash in STM32 can be found on page 7 of the Flash programming manual.
I've a register space of 16 registers.
These are accessible through serial bus (single as well as burst).
I've UVM reg model defined for these registers.
However none of the reg model method supports burst transaction on bus.
As a workaround
I can declare memory model for same space and whenever I need burst access I use memory model but it seems redundant to declare 2 separate classes for same thing and this approach won't mirror register values correctly.
create a function which loops for number of bytes iterations and access registers one by one however this method doesn't create burst transaction on bus.
So I would like to know if there is a way to use burst_read and burst_write methods with register model. It would be nice if burst_read and burst_write support mirroring (current implementation doesn't support this) but if not I can use .predict and .set so its not big concern.
Or can I implement a method for register model easily to support burst operation.
I found this to help get you started:
http://forums.accellera.org/topic/716-uvm-register-model-burst-access/
The guy mentions using the optional 'extension' argument that read/write take. You could store the length of the burst length inside a container object (think int vs. Integer in Java) and then pass that as an argument when calling write() on the first register.
A rough sketch (not tested):
// inside your register sequence
uvm_queue #(int) container = new("container");
container.push_front(4);
start_reg.write(status, data, .extension(container));
// inside your adapter
function uvm_sequence_item reg2bus(const ref uvm_reg_bus_op rw);
int burst_len = 1;
uvm_reg_item reg_item = get_item();
uvm_queue #(int) extension;
if ($cast(extension, reg_item.extension))
burst_len = extension.pop_front();
// do the stuff here based on the burst length
// ...
endfunction
I've used uvm_queue because there isn't any trivial container object in UVM.
After combining opinions provided by Tudor and links in the discussion, here is what works for adding burst operation to reg model.
This implementation doesn't show all the code but only required part for adding burst operation, I've tested it for write and read operation with serial protocols (SPI / I2C). Register model values are updated correctly as well as RTL registers are updated.
Create a class to hold data and burst length:
class burst_class extends uvm_object;
`uvm_object_utils (....);
int burst_length;
byte data [$];
function new (string name);
super.new(name);
endfunction
endclass
Inside register sequence (for read don't initialize data)
burst_class obj;
obj = new ("burstInfo");
obj.burst_length = 4; // replace with actual length
obj.data.push_back (data1);
obj.data.push_back (data2);
obj.data.push_back (data3);
obj.data.push_back (data4);
start_reg.read (status,...., .extension(obj));
start_reg.write (status, ...., .extension (obj));
After successful operation data values should be written or collected in obj object
In adapter class (reg2bus is updated for write and bus2reg is updated for read)
All the information about transaction is available in reg2bus except data in case of read.
adapter class
uvm_reg_item start_reg;
int burst_length;
burst_class adapter_obj;
reg2bus implementation
start_reg = this.get_item;
adapter_obj = new ("adapter_obj");
if($cast (adapter_obj, start_reg.extension)) begin
if (adapter_obj != null) begin
burst_length = adapter_obj.burst_length;
end
else
burst_length = 1; /// so that current implementation of adapter still works
end
Update the size of transaction over here according to burst_length and assign data correctly.
As for read bus2reg needs to be updated
bus2reg implementation (Already has all control information since reg2bus is always executed before bus2reg, use the values captured in reg2bus)
According to burst_length only assign data to object passed though extension in this case adapter_obj
We send bitmaps from our Silverlight client to the server to be saved, using a WCF-RIA defined service operation. Our DomainService class looks a little like this:
[EnableClientAccess()]
public class CBitmapSavingService : DomainService
{
public void SaveBitmap(string bitmapGuid, byte[] pngBytes)
{
// Save PNG on server file system
}
}
Works fine, until we get a large bitmap. Then we get a 'DomainOperationException' exception.
I suspect that we are surpassing a size limit for either the parameter or the message.
Can I reconfigure my service such that larger bitmaps can be sent from the client with WCF-RIA-Services?
I made the following change to my web.config file:
<httpRuntime requestValidationMode="2.0" maxRequestLength="6225920"/>
and it worked.
(why 6225920? Size of 2048*760 bitmap before compression, I gotta choose something)
I found the answer on another site: http://forums.silverlight.net/forums/p/186772/440463.aspx
This is only intended as a short term fix for us, because we don't really want such large bitmaps on the server. I plan to make a client side change, such that the picture type (PNG or JPEG) and quality will be changed to create an image within a defined maximum size.