Electrical Engineering

Questions tagged [addressing]

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MCP2221A Sending Register Address

I am trying to control 2 IC(PCA9555) via i2c. The i2c lines can be accessed by a connector. Also i have a usb connector and it is connected to a mcp2221A. The MCP's i2c pins are common with the ...
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1answer
47 views

How to read this memory map of LPC1769 microcontroller?

I'm trying to understand the memory map of the LPC1769 microcontroller using the official NXP datasheet. The screenshot below shows at 0x00004000 to 0x00008000 there is 512kB of flash memory mapped, ...
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1answer
84 views

Can a memory chip have a certain starting address

In my book there is a question stated: Can a memory chip of capacity 512 KB have the starting address 2B0000h? To me this seems like an incomplete question with a wrong answer in the book. The ...
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2answers
69 views

Memory-mapped IO vs Port-mapped IO in microcontrollers

I've been reading about external peripheral mapping to microcontrollers. I understand that memory-mapped IO means that the same address space in the microcontroller can be used for internal memory ...
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4answers
200 views

8/16/32 Bits of microcontrollers [duplicate]

I am new to the field of embedded systems. Recently I was learning about the differences between different bit size (8, 16, 32) microcontrollers. What I found was that the size of bit indicates the ...
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1answer
59 views

Multiplexer to switch between many sets of 8 channels [closed]

I have many (up to 16) 8-channel "buses" (not digital, but analog) each with signals which I want to read with a single 8-channel analog-to-digital converter (ADC). I would switch between these ~16 ...
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1answer
148 views

Microprocessor architecture bits vs bus sizes

I am ready following on this website: "Another big difference between 32-bit processors and 64-bit processors is the maximum amount of memory (RAM) that is supported. 32-bit computers support a ...
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1answer
71 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
78 views

Addressing 45 Inputs Down to 6 pin Output

I'm looking for a chip which could minimize ~45 button inputs down to an 6 pin input for use with Raspberry Pi. I know this is a simple problem and it has likely been solved before, but as an ...
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1answer
74 views

How many external devices can be linked to a CPU with n address buses and m data buses?

(Hypothetical) Let's say there is a CPU with 8 address lines and 8 data lines. If each external device has 128 accessible registers, how many external devices can be linked? For 8 address lines, I ...
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98 views

Finding address space

Could somebody please explain how to find the address space for the RAM, Sensors, Alarm and ROM? :) The answer is supposed to be ROM: 0000-1FFF RAM: 2000-3FFF Sensors: FFF0 - FFFF Alarm: FFFE
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382 views

Does pin A15 on a Z80 tell if the CPU is addressing ROM or RAM?

I am designing a simple, hobbyist single board computer similar to an Arduino using a Z80 CPU. The trouble I am running into is how the CPU addresses memory. I know that the Z80 uses pins A0-A15 to ...
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4answers
732 views

advantages of PC-relative addressing

I have read somewhere: "The advantage of using relative mode over direct mode is that relative addressing is a code which is position-independent, i.e. it can be loaded anywhere in memory without ...
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2answers
50 views

Address bus, databus: how much storage direct accessible

I have a CPU with a 32 bits data bus and a 21 bits address bus. I would like to know how much storage I can connect to this CPU directly. Does this depend on the address bus width, because I can ...
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618 views

Why are the SRAM data and address pins numbered? [duplicate]

As far as understand, it would make no difference to the operation of an SRAM if you mixed up the order of the address or data pins. E.g. http://www.farnell.com/datasheets/1911297.pdf?_ga=2.220805788....
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1answer
80 views

Would a parallel EEPROM ever output a value that it does not contain?

I understand that when the address input to a parallel EEPROM changes from A to B, the output may show results that aren't the contents of either A or B, for a few nanoseconds. Are these spurious ...
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1answer
94 views

inverting address decoder with low after high

I have an 74137 address decoder and know how to build one like that from basic gates. But in my use case the address decoder is connected to the enable pins of a number of bus drivers and I fear this ...
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2answers
263 views

I2C Addressing after device address is known

I have an I2C device that I know the address is 0x70 (probed when connected to Raspberry Pi using i2cdetect -y 1). My issue is that the bytes I want to look at need to be called in WiringPi. The ...
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1answer
297 views

Cascaded i2c address translators?

I am trying to connect many (~80) ToF distance sensors VL53L0X onto a single i2c bus. They have the default i2c address 0x52, which is programmable, but not persistent. Thus I have a choice between ...
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1answer
591 views

Understanding GDDR5 clamshell mode

Let suppose a 256 bit memory controller is installed on a PCB with GDDR5 memory modules. In normal mode you can split the lines into 8 group of 32 bit and drive 8 modules x 1Gbit (128 MB) = 1 GB of ...
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1answer
327 views

Design logic circuit to address 2 x 512 kB RAM and 2x1024 MB RAM with 36 address lines? [closed]

How do you address 2 x 512 kB RAM and 2 x 1024 MB RAM with 40 address lines? Memory is byte addressable, problem is to find out enough address lines to address all 4RAM and designing appropriate ...
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2answers
161 views

AT28C16 Interface Help

I pulled an AT28C16 from an old KVM switch and have managed to wire it up like so: A0-10 -> GND CE -> GND WE -> 5V OE -> GND VCC -> 5V GND -> GND I/O0-7 -> Floating. Plugged by hand to level meter ...
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1answer
120 views

Controlling motors same as WS2812b works (Neopixels)

Im a beginner and trying to achieve a weird scenario (Could be). There is around 30 tiny DC motors for each of those I need to make it individually controllable. Same as WS2812b led works. How can I ...
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1answer
242 views

What is slave select signal on the APB bus for?

I am currently working on an APB BFM and I have a question regarding the bus protocol. I understand every slave on APB bus has its own unique address space, where its internal registers are mapped. ...
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1answer
283 views

I2c slave address confusion?

Can someone explain which address will be used for ADV7511 for I2C if it is stated that it is either 0x72 or 0x7a in adv 7511programming guide [page 16]? If I am right, we send 8 bits per transfer, ...
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1answer
62 views

Relate Bin file (read from uC) to map file

We have a AT32UC3C1512 presenting a Failure, part of the analysis that is normally performed to isolate the failure is to perform ABA swap of components, we have performed the swap in several ...
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2answers
217 views

what is an “Adressable” I2c device, and what does it mean?

The MCP3021 is a standard 10-bit ADC with an I2C Interface. It's datasheet can be found here. In the general description, it says: The device is also addressable, allowing up to eight devices ...
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2answers
2k views

PCI device address actually means slot address? And when does PCIe slot get its' address?

I'd like to clarify how the configuration address space in PCI and PCIe works. Namely, a PCI peripheral on a bus is addressed with device:function pair (the ...
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2answers
2k views

Arm mode and Thumb mode makes the PC's bit 0

The ARM and Thumb modes are word-aligned and halfword-aligned. I understand this means that if it's in ARM mode, the start of addresses must be divisible by 32, and if it's in Thumb mode it has to be ...
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1answer
43 views

Measure resistance (make connection) between array of points

I have array of connectors where I will plug in various types of resistors, I would like to be able to connect to each of the points as addresses and measure resistance between these points. Here is ...
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3answers
514 views

Why can't you use microprocessor I/O pins as chip enable pins for ROM and RAM?

I have been reading a textbook on Embedded systems called An Embedded software primer by David E Simon (great book btw). I am trying to answer questions after each chapter, I got through first 2 ...
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2answers
285 views

Understanding DDRn SDRAM

So I am basically trying to grasp/confirm my grasp of SDRAM and DDR. So basically I understand that there is going to be some chips each with up to 8 banks (so kinda like 8 chips internally?). For ...
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1answer
876 views

Proper way of storing a register address on ARM Cortex M4?

I am writing a program on STM32F4 Discovery where I have to store address of Timer's CCR register into a pointer and then change register via this pointer, ie ...
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1answer
2k views

What happens If the interrupt occurs during the execution of HALT instruction?

Consider the following program segment on a hypothetical processor . I have this question in my course CS201. Suppose this processor has 32 bits Load/Store operations, ALU operations is 16 bits and ...
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1answer
524 views

I2C address selection in PCA9685

I am using PCA9685 in a project. 3 are on the same i2c bus and thus I need to change the address of individual ICs. It has 5 selectable address bits as shown in the figure below: The address will ...
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4answers
487 views

Clarification regarding I2C address

I was going through the following link which describes the "I2C address allocation table" http://simplemachines.it/doc/IC12_97_I2C_ALLOCATION.pdf Upon reading the aforementioned information table I ...
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1answer
76 views

Choose “safe” section of DDR memory in ZC702 board

I can not fully understand what section of the available external memory is safe to assign for a VDMA on the ZC702 board. I need to dedicate 4MB of memory for the three frames (640*480* 4bytes * 3 ...
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2answers
652 views

How to setup slave addressing with a HT16K33 in Proteus?

I have setup the following circuit in Proteus : A PIC12F1822 is connected to a HT16K33 using an I2C bus. I want to configure the HT16K33 to use the following address : ...
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2answers
174 views

considerations about little endian processor and opeartions on registers

Processor is little-endian. Under followings addresses we have following values (hexdecimal format): 1000: FA 1001: 46 1002: 26 1003: C3 Now, processor is ...
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3answers
710 views

8086 memory decoder logic

I started creating a scheme for 8086 based computer now I'm in trouble with memory addressing. I know a 20 bit wide addressing line can address up to 1024 KB of RAM and that pin A0, when high, select ...
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2answers
433 views

Is this address decoding circuit correct?

The problem is to design an address decoding circuit for two 4Kx8 RAM chips at the 2050H . We have 16 address lines. So, for 4Kx8 RAM we need 12 address lines to address the memory. Remaining can be ...
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1answer
1k views

Managing I2C address conflicts with multiple MCP23017 on the same bus

I'm using a Raspberry Pi with the I2C master and I successfully wired 8 different MCP23017 chips, each with their respective addresses by setting the last 3 bits of their 7 bit addresses. They are all ...
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2answers
223 views

Big address space and small physical size?

The Intel D1000 MCU datasheet says: The MCU has 4 kB of data flash and 32 kB of code flash. Code flash occupies the address range 0x2000 0000 to 0x3FFF FFFF and is aliased throughout. It is ...
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2answers
1k views

4-bit bus address selection via analog input pin: Monte Carlo simulation shows overlapping address values

I designed a small sensor PCB for my master thesis with an ATtiny44 microcontroller. I need about 200 of these boards for my application and 16 are always locally connected to controller board. The ...
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1answer
181 views

How do I2C modules select between more than 2 slave addresses?

I am using the TMP112 I2C temperature sensor and noticed that you can choose between 4 slave addresses by connecting the A0 pin to V+, GND, SCL, or SDA. How does the sensor tell between SCL, SDA, and ...
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1answer
276 views

A computer system has RAM of 32K bytes and 64 peripherals. What is the number of distinct addresses required? [closed]

Is it correct to assume that the number of addresses for 32k of ram is 2^15 addresses? Then for the peripherals is it 2^6 addresses?
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1answer
73 views

MSP430 - how to check addressing types

I'm programming a MSP430 in C language as a simulation of real microcontroller. I got stuck in addressing modes (https://en.wikipedia.org/wiki/TI_MSP430#MSP430_CPU), especially: Addressing modes ...
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2answers
131 views

ECE - Study Guide: Physical Memory addresses how many bytes?

Attempting to do this study guide, but i'm not finding too much help online. Any help is welcome, and a explanation would be nice, as my text book does not describe how to answer a problem given the ...
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1answer
914 views

What's the difference between passive matrix and active matrix?

Both passive matrix and active matrix use "m+n" row-column addressing method to eventually switch individual components. So what makes one active and the other one passive?
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890 views

Problem with glue logic/memory decoding on a 6502 project

I have a problem understanding the following schematic, specifically the "Glue Logic(Memory Decoding)" section in the lower half middle: This is a simple breadboard computer based on a 6502 CPU with ...

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