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Questions tagged [memory]

Consider instead more specific tags, e.g., dram, sram, flash

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Problems with understanding memory map STM32F446RE

I have a problem with the understanding of the memory map of the STM32F446RE. In the datasheet is the system memory (0x1FFF0000 - 0x1FFF7A0F) 30kb big. But in the AN2606 the system memory is only ...
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2answers
77 views

Make a single bit memory using transistor

I want to make a single bit memory using transistors. And if can, I want its data is still stored. Thank you! I am very sory that English isn't my mother language. Sorry for any mistake.
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2answers
70 views

STM32 Memory Alignment unclear

As I'm reading the Mastering STM32 Book, I came across this graphic describing the memory map So what I'm trying to figure out is whether my understanding of memory is wrong, or if the graphic is. ...
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25 views

If the Sense Amplifiers structure is the same as an SRAM cell's, why the differential voltage on the bit line gets amplified?

source How you can see the structure with 6 transistors of a Sense Amplifier (SA) is the same as a SRAM cell, but this latter causes a little variation on the bitline voltage that the SA will amplify....
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1answer
35 views

External bus interfacing

This lab requires us to extend the memory and I/O ports on our µPad using our EBI backpack. What I'm confused about is how the fully address decoded SRAM will differ from the partially addressed i/o ...
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5answers
1k views

Heap allocation on a microcontroller

I'm working on STM32F303VC. How does the heap allocation work? When I declare the arrays outside main() it allocates them on the heap - SRAM - 0x2000000 and forth in this MCU. But what determines the ...
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1answer
60 views

Purpose of enablers

I was reading the following book: But How Do It Know? The Basic Principles of Computers for Everyone I learnt that a memory bit ( a special wiring between 4 NAND gates) helps the computer remember ...
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1answer
49 views

What are the parameters I should consider while selecting a Memory IC? [closed]

I have a Microcontroller which needs to be connected to a memory using SPI Interface. What are the major parameters that I have to consider while choosing a Flash IC?
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1answer
77 views

Assembly language, accessing bytes of memory

I have some memory address 0x00000100 that I want to read from. The lower 4 bits read from this address indicates the states of 4 buttons - So bit 0 shows the state of button 0, bit 1 shows the state ...
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2answers
108 views

SMP, NUMA, local memory - limits on numer of processors

I consider what are limits on number of processor in following models of shared memory: a. each processor has only own local memory. b. SMP c. NUMA I can't see any limits. Am I wrong ?
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27 views

STM32 with Winbond W25Q80DV Write Data Issue

I am trying to store data in SPI FLASH MEMORY of WINBOND W25Q80DV. I am able to read status registers and manufacturer ID successfully but can't able to write data into it. The procedure I followed: ...
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3answers
576 views

Storing an LED's previous state even when power is removed

Storing an LED's previous state even if power is removed I want to build a simple circuit that consists of 2 push buttons and an LED. I want the LED to turn on when one pushbutton is pressed and off ...
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1answer
53 views

gcc __attribute__ section not working?

I'm working on a Zynq Ultrascale+ MPSoC and trying to play around with the on and off chip memories. In the following program, I'm trying to place only variable 'x' into OCM (on-chip-memory) where ...
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3answers
2k views

What information exactly does an instruction cache store?

Processors use both data and instruction caches in order to reduce the number of slow accesses to main memory. However, while it is clear to me that the data cache's purpose is to store frequently ...
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1answer
28k views

Meaning of control pins: CE, OE, WE

Just understanding some syntax. On my Ram (6116) and Rom (27C64) it has a asserted low CE and OE pins. These I believe are control pins. I'm assuming to use the RAM for example, chip enable (CE) has ...
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47 views

How do I produce WE in this diagram?

I have designed a memory system that has 10KB ROM followed by 6KB of RAM. The ROM begins at 0000H. I had to use two 4K x 8bit ROMs and one 2K x 8 bit ROM. I also have to use one 2K x 8bit RAM and a 4K ...
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2answers
115 views

How can I determine how much memory a function occupies?

How can I view how much program memory a function is occupying ? I am currently at 95% program memory usage and do not have a licence to enable optimization. I am looking to find out which functions ...
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1answer
554 views

using generate statement in verilog

I am using nested for loops using generate module for creating multiple instances of sub-modules in verilog this is for finding 4x4 determinant. I generated the sub-modules with inputs given ...
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2answers
308 views

Why have apparent memory bitflips in non-ECC memory not increased?

Back in the early 2000s I remember asking about why it was so important that servers use ECC memory. The prevailing wisdom at the time was that systems with lots of RAM would be, statistically, more ...
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88 views

Handling Large Variable Data with a Microcontroller

What is good practice for storing and manipulating variable data in a microcontroller circuit when the data may exceed microcontroller working memory? In my application, I am designing an access ...
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1answer
43 views

Address decoding different bank sizes in 64K memory

I'm doing a small Motorola 6809-based computer project, and since I'm a bit rusty when it comes to boolean algebra I'm wondering if I'm doing my address decoding a bit too complicated for my simple ...
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2answers
75 views

I've seen many conflicting answers online: For optical storage, does a pit represent a '1' bit or does a land represent a '1' bit?

I've seen many conflicting answers online so: When reading an optical disk, which one of these is true: A 'pit' represents 1 and a 'land' represents 0 or A 'pit' represents 0 and a 'land' ...
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16 views

Chaging EA/VPP by software on Intel MCS-51/8051

I'm designing a circuit that uses the combined Program/Data bus from Intel MSC-51 as advantage. By the MCS-51 specification it has an internal 4K ROM and a EA/VPP pin that if set to high will access ...
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1answer
13 views

Is it possible to add a UID to M45PE10-VMN6?

Is it possible to add a UID to p/n M45PE10-VMN6 ? We need to add this security feature to these chips, but I am assuming it needed to be done at factory. Originally we could have purchased p/n ...
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2answers
1k views

Will reading serial flash memory wear it out?

I know that a flash memory has limited write cycles. Does it also have limited read cycles? Datasheets of most serial flash memories (like SST25VF series) mention endurance cycles. Does this ...
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1answer
26 views

Can more than one memory device transmit on the data bus at once?

I know that in general only one device can transmit over the bus at once, but if they are all memory devices, can they act as one? I have four 256x8 chips, which I think means that I have 256 cells ...
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1answer
77 views

Interfacing 16-bit SRAM/MRAM with Arduino Mega

I a looking to interface a MR2A16A 4Mb 16-bit MRAM with an Arduino Mega. I am new to interfacing with memory chips and would like some advice from someone more experienced than myself. I am not ...
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1answer
109 views

How to increase memory on the FPGA board?

Situation I'm running a driver code driver.cc on the FPGA board (PYNQ-Z1) but it gives an error in the middle of the code where the code calls to ...
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1answer
36 views

Reading memory array

im new to memory cells. I have taken the below image from a video, i wanted to ask in the video he explains that the MUX can select 8 bits, but how is this even possible? The output of a MUX is always ...
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1answer
90 views

Reading a MD25Q128SIG SPI flash memory with raspberry pi

I'm trying to read a MD25Q128SIG SPI flash memory with my raspberry pi, you can find its datasheet here: http://www.firstjit.com/Uploadfiles/20160121152131319.pdf Here are raspberry pi pinouts: Here ...
6
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8answers
3k views

What prevents the construction of a CPU with all necessary memory represented in registers? [duplicate]

Modern CPUs employ a hierarchy of memory technologies. Registers, built into the chip have the lowest access times, but are expensive and volatile. Cache is a middle-man between RAM and registers to ...
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1answer
111 views

Memory chips, are the bits of a long word stored contiguously?

I am reading Structured Computer Organization, 6th edition by by Andrew S. Tanenbaum and Todd Austin. Chapter 3.3.5 talks about memory chips. I'm confused about the following paragraph, which relates ...
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2answers
5k views

DDRx Memory: Memory Clock vs I/O Bus Clock?

When referring to DDR/DDR2/DDR3/DDR4 memories, I am not able to understand the difference between memory clock and I/O clock. As per: https://en.wikipedia.org/wiki/Double_data_rate DDR-200 - Memory ...
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1answer
93 views

How to find the memory capacity? [closed]

A memory component spans the address range 0x00400000 to 0x007FFFFF, what is its capacity? I only know the calculate the two ...
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0answers
46 views

S25FL512S flash driver, read or write not working correctly

I am trying to write a driver for an S70FL01GS chip, which is two stacked S25FL512S chips. I am successfully reading status register, SFDP register, RDID, etc. I am also able to toggle (and verify) ...
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1answer
88 views

Core rope rom not working

I am trying to make my own core rope rom, according to the link. I have 15mm ferrite cores, which I wound about 30 times with 1mm magnet wire. I thread the primary ( also 1mm wire) through one of ...
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1answer
107 views

How do memory seats keep track of their position?

I was wondering how do memory seats keep track of their position. Since this kind of equipment existed in 1990's cars, it must be simple yet ingenious. I have been thinking about this for quite a time ...
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4answers
130 views

How can we determine memory usage of a microcontroller

How can we determine how much memory is being used, or will be used by firmware in a microcontroller? What tools can support this? Generally we don't use dynamic memory in embedded systems, but how ...
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1answer
170 views

How to write STM32F4 OTP Area

I am reading the reference manual page 75 that shows the flash memory organization of STM32F4 MCUs. There is an OTP area of 528 Bytes in it as shown in the image: Is it possible to write on this OTP ...
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24 views

Synopsys Technology File (STF)

I am using a memory IP block from STM. The manuals of the memory IP has talked a lot about Synopsys Technology File (STF), though, with no info on how and where to use it. Among all files related to ...
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21 views

Can FOTA be performed by changing the execution point of the code i.e, changing the program counter in lpc1759

For FOTA can we divide the memory into two blocks, eg : block A and block B. And whenever there is a new version of firmware detected, we shall change the execution point of the code. Is this ...
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1answer
61 views

Is a multiplexer needed to read from memory

we need to enable a register to write into that register, which is done using a decoder. even if we enable 1 register using decoder, given that RD(bar) is 0, all registers can still produce an output. ...
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2answers
171 views

Designing a RAM, using 4x2 chips, with a 8 address capacity

This is a typical exam question, and I've seen some very helpful posts about, but I still have a lot of doubts. Given an integrated circuit of certain dimensions, for this example a 4x2, I have to ...
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0answers
50 views

EPCQL controller

I am trying to access in read and write my EPCQL-1024 from simple soft running in NIOSII. I have the Altera Serial Flash Controller I configured in QUAD mode connected from its avl_csr and avl_mem to ...
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0answers
64 views

How to use Altium Multi-Board to define SODIMM board and socket connections?

I am attempting to use Altium 18.1.9's new "Multi-Board" feature to connect a 200-pin SODIMM board ---> to a SODIMM socket connector ---> on my mainboard PCB. This Altium article is just about the ...
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2answers
168 views

Finding the address of structure knowing the address of one of it's members in C

This sounds like a little too far fetched, but is there any possibility to find the address of a structure, if the address of one of it's members is known? The struct itself contains different data ...
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1answer
181 views

Atmel SAME70 SDRAM Memory Mapping

In the Atmel SAME70-XPLD board, there is a 2MB (2 bank x 2K row x 256 col x 16 bit) SDRAM (ISSI IS42S16100F-5BL). It is connected as follows: I don't understand why the A0 pin of the SDRAM is ...
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2answers
62 views

Maximum cells in a row in a SRAM memory array

I was considering designing an SRAM memory array. For my design to be useful in a certain system, I need to have several cells in a row (e.g. 1024, 2048). In textbooks I have seen examples of arrays ...
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2answers
256 views

What does the number of “ single-word instructions ” mean on a MCU's memory specifications?

I have copied the following sentence from a PIC MCU datasheet: "PIC18(L)F26K22, PIC18(L)F46K22: 64 Kbytes of Flash Memory, up to 37,768 single-word instructions." the question is what does " 37,768 ...
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0answers
35 views

Finding the memory polynomial model coefficients

I want to build a memory polynomial model given that I know the corresponding output signals for known input signals. What is the easiest way to find the coefficients of it? And how do we take the ...