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Questions tagged [register]

A special, high-speed storage area within the CPU.

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1answer
21 views

How to modify BRR and BRSS registers to stm32f4 from stm32f103

I'm trying to modify stm32f103 2x16 lcd library to stm32f4. There are BRR and BSRR register on stm32f103 but there aren't similar register in GPIO_TypeDef structure on stm32f4 so i don't know how to ...
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30 views

Renaming a special register

I noticed that RISC-V, like some other RISC architectures, by convention treats register 1 specially, using it as the link register, holding the return address for function calls. If most code ...
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1answer
57 views

[Updated]How to select the values to move in assembler?

I'm trying to make the led blinks on the tm4c1294ncpdt, so the basic idea its to make 2 routines , one to select the GPIO port (in this case the F) and other to keep up on and off. the setup routine ...
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42 views

Register readback for ADC WM8253

I am trying to read the contents of register written in serial mode of WM8253 using SPI in Basys 3 FPGA. Link to Datasheet. I'm reading from register '011100' but the result that is read is always "...
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4answers
3k views

What stops an assembly program from crashing the operating system? [closed]

First of all, I am a beginner, so if this question sounds silly, please point out the incorrect assumptions. From what I understand, the job of an operating system is to manage hardware and the ...
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1answer
59 views

74hc595 sinking, not sourcing

I'm trying to get a sn74hc595n working with an arduino Due, eventually I will be hooking up each output to an NPN to drive Nixie tubes (I am switching my design from a due to using a esp8266 so I need ...
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1answer
28 views

When to monitor UxSTAbits.TRMT and UxSTAbits.UTXBF

According to the reference manual on UART for PIC here(page 7), the UxSTA register have two read-only bits; TRMT and UTXBF. While writing a simple transmission program over UART, I didn't notice any ...
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1answer
41 views

MAX17205 DevName reading wrong, but other default value is correct. Why?

I am using the battery fuel guage MAX17205 through I2C bus. The Device Name register that I read from it seems have a different value than what the datasheet states: I am reading a 0x2a7c, but it'...
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19 views

Clk pulses needed to retrieve data in registers

I know that to store n bits of data in a SISO register , n clk pulses are needed . And to retrieve the data only n-1 clk pulses are needed because 1 bit is already available at the output . In a SIPO ...
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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
40 views

Where the appropriate word size is selected for the operand?

This question is about a 32 bit Intel Chip using x86 assembly. My question specifically is what happens when you do the mov reg, mem instruction where the memory operand is a word (16 bits) from DRAM. ...
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1answer
30 views

Initial register value in synthesized design is always 0

I'm using Altera Cyclone IV EP4CE6 as my FPGA. Compiling the design in Quartus Prime 18.0.0 Lite Edition. The State register in the below module appears to be 0 ...
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1answer
117 views

Multiplexer handling 16 bits

Design the VHDL components (Register, Decoder, and two Multiplexer 16 bit) and interconnect them to build a register file. The schematic shows only four registers. Your solution should implement ...
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36 views

STM32F4xx, How to use RTC correctly?

I'm trying to run RTC, but there are two problems. 1) It is impossible to write the security key in the WPR register. 2) It is impossible to set the time and date in the TR and DR registers. I tried ...
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1answer
47 views

PISO shift register with first input

I have on my board two PISO shift registers in series, giving an output train of 16 bits. The problem is that the order of the bits is reversed compared to what I need. That means, the last input of ...
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0answers
60 views

SPI problem with STM32F103

I am trying to connect blue pill board(master) to arduino nano(slave) over SPI and read what I have sent on serial monitor. However I haven't been able to get SPI working. I run a timer to generate an ...
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2answers
54 views

What's the difference between a hardware register and a shift register?

There are two different wikipedia articles but they don't articulate the difference very clearly. Is the main difference that the shift registry uses a clock?
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3answers
93 views

HDL code convention for register resets

When it comes to (synchronously) resetting registers in HDL (I'll use Verilog), is it considered bad practice to code the reset combinatorially? As far as I can tell, the following two snippets are ...
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3answers
59 views

Phase register in phase accumulator

In the following flow diagram: Is the "phase register" a one-bit register? What does it basically do with that summation mark? What type of register is it? I basically do not know what the phase ...
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1answer
41 views

what does “ports can be registered” mean? For circuit design

I have a homework. I must design a circuit that makes addition with signed and unsigned numbers. I will use registers. I need two output ports. It says "8-bit output ports (2 ports: one for unsigned ...
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3answers
64 views

Clock domain cross and metastablilty problem

I understand the problem of metastability and understand that we can't get a stable value in a bounded time so we need unbonded time but it is not practical, so we put another flip flop with no ...
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2answers
1k views

Finite State Machine FSM

I understand how to make state diagram and make combinational logic (gates) to get a boolean equation for the next state bits and the output bit, but what is the function of ROM here ?
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1answer
72 views

When does a register need to get a load control-signal in order to be updated at the next clock? [closed]

I know this is a pretty basic question, but I didn't succeed to find an unambiguous answer. Does a register need to get load signal in the cycle in which the new value computation is made? or at the ...
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0answers
23 views

What is the tradeoff between number of register files and logical register specified in the ISA?

As the limited number of logical registers are opened to the user and compiler, it incurs the false dependency problems such as WAW and WAR. Therefore, to solve this problem, lots of ...
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1answer
214 views

Error (suppressible): (vsim-3601) Iteration limit Quartus

I have created a Simulation of a 4 bit register in quartus. Each of the four D flip flops test fine by themselves, but when I test 4 of them connected together into a register, I get the "Error (...
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2answers
832 views

What is this array-like notation of registers in datasheets?

I am reading BMP280 datasheet (pressure&temperature sensor). On different pages they use the following notation: $$register\text{_}name[a:b]$$ where a, b are integers. For example, on page 13 "...
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2answers
84 views

Are memory-mapped registers actually implemented as real registers?

I am currently trying to better understand microcontroller-architectures and I am particularly studying the ARM cortex-m3 right now. What I have always wondered is, if memory mapped registers are ...
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1answer
85 views

Pull up/down a pin on a PCA9536 does not register?

Quite a obscure question here, concerning a very specific I2C expander IC, however I believe that this example can be replicated with most expander bus ICs. I am using a PCA9536 to switch the 4 pins ...
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1answer
921 views

variable should not be used in output port connection

I searched random verilog heirarchy to understand how to properly instantiate modules. I found one on https://www.altera.com/support/support-resources/design-examples/design-software/verilog/ver_hier....
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1answer
110 views

Q: Digital potentiometer MCP4162

I am having a hard time understanding the MCP4162 Datasheet. The application for the digi pot is have an Ardunio to control the wiper resistance so I can have a constant desired output voltage ...
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1answer
286 views

What will happen if a dependent voltage source in parallel with a dependent current source?

What will happen if a dependent voltage source in parallel with a dependent current source. like dependent voltage source: 4Vx and current source 3Ix in parallel.
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1answer
28 views

BQ76PL536A: Stopping measuring voltages and temperatures

I am testing a BMS design with multiple slave boards each containing one bq76PL536A connected to a common CAN bus through a ATmega32M1 MCU and a ISO1050DW isolated transceiver. The problem I am facing ...
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3answers
92 views

How to find current in this circuit passing through 4ohm resistor

Below I have added my solution after the question so please let me know how I can solve it after the last step: These steps to follow to solve the question from where i left in my post , FYI :As ...
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1answer
84 views

Special Function Registers value expressed as Hexadecimal & Bit shift

I was wondering if someone could help me solve one problem, because I am very new to this and I was given the code of a former programmer to work with. I'm trying to figure out the value of 0x8008 &...
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2answers
513 views

how to initialize a vector of registers in verilog?

I want to initialize the following 16-bit registers in my module. reg [15:0] coefficient[4:0]; I used concatenation operator to do this: ...
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2answers
282 views

VHDL 4-bit Shift-and-Add Multiplier Buffer and Out port error

I am working on a creating a 4-bit Shift-and-Add Multiplier. I am getting this warning message - "WARNING:HDLParsers:3555 - "//filer1.egr.msu.edu/samarar1/ece230/Project05/Project05.vhd" Line 220. ...
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1answer
1k views

What is increment/decrement address latch in 8085

Can you please explain about increment/decrement latch in 8085. I am currently studying registers and encountered this in the array of register section. Here are the things i found when i googled and ...
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1answer
35 views

verilog register with clock

Now, I've been learning Verilog but I got stuck with some easy problems. always@(posedge clock) if(reset == 1’b1) leds_r <=0; else leds_r <= leds_r + 1; I ...
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2answers
128 views

Will my decimal to binary converter work

I got into electronics recently and I hope to make a 8 bit ripple carry adder with a decimal input and output. This input is the first schematic I designed from scratch without a tutorial to go off ...
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2answers
291 views

CPU register count and access time [closed]

It has been suggested that one of the reasons typical RISC CPUs stop at 32 architectural integer registers, despite a 32-bit instruction having enough spare bits to specify 64, is that a larger ...
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1answer
35 views

I-type register format maximum size of a constant

The above picture is an I-type format register. I am confused as to why the largest constant possible is $$2^{15}$$ Should the largest possible constant be $$2^{16} -1$$
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1answer
458 views

Clarification on R, I, and J type Instruction formats in MIPS

I would like some clarification on some concepts of register types, to know if I understand it correctly. If I had a 32-bit CPU. Would that mean that the max number of operations that can be ...
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2answers
86 views

Design an instruction using Thumb-2

I'm studying the Cortex-M3 of ARM. The problem statement reads: We're going to use a Harvard architecture with the following addressing capabilities: 32M words of code and 16-bit data words. The ...
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2answers
230 views

What does the square brackets mean?

In this diagram: What does the S[2:0] mean? I think it is the state but why is the state in 3 bits? What does the 2 and 0 mean? Cheers!
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1answer
2k views

How to dynamically adjust a timer with STM32

I've got this timer (TIM4) that's in PWM mode. I'm outputting one PWM channel and i want to wait a bit, and then grab the latest ADC samples from a DMA conversion. TIM4 -> ARR is 4096 TIM4 -> CCR1 ...
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2answers
67 views

microproccessor 8085

What is the need of enabling 8 bit register in memory using address bus to read data from it?Enabling is required to write data into register and after that to read can't we just provide read signal ...
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2answers
2k views

STM32F103 temperature sensor calibration addresses

I am new to ARM world and using STM32F103C8T6 ARM microcontroller. I want to get micro's internal temperature sensor working. I am able to get some data from it but I'm not sure how to convert these ...
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1answer
117 views

Why is the stored value in each D flip flop reconnected to the input in a buffer register?

Like can one not just connect a single AND gate with the load and X input instead of complicating by reconnecting the output and using another OR gate? Will it be logically the same? or is it that I ...
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2answers
130 views

Register map using C for a MAX30001 analog front end

I am trying to follow the best practices in register mapping. I have a MAX30001 analog front end for ECG applications (Datasheet) and in page 38, there is a table that contains user command and ...
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0answers
177 views

libmodbus modbus_read_bits() returns illegal function

It is all okay when it comes to read registers with: modbus_read_registers(ctx,0,32,destination); It gives me values of 32 different registers. But when it comes ...