Questions tagged [register]

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

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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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95 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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298 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
3k 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
71 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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134 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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142 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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214 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 ...
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1answer
28 views

Negative recommended intensity on read of logical 1 D-latch octal register

I am very new to electronic design, even if I do have some bases in electric design. For an hypothetical circuit I'm designing, I need some D-latches to operate as 8 bit registers. Searching for ...
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2answers
177 views

7400 chip register with common in/out pins

First of all, I don't know if this kind of question is allowed here, so sorry if it isn't. I am looking for a 7400 series register which has common in and out pins (like for the RAM ou EEPROM: ) with ...
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169 views

The value of the TCC counter on an ATSAM controller always reads as zero

I use an ATSAMD21 to generate a custom signal with the help of a PWM generator. Basically, I set up TCC0 as a PWM generator, and use its overflow interrupt to set up the CC registers for the next ...
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306 views

Unable to set Pin Change Interrupt on ATmega328p

so I am working on learning some AVR programming with the ATmega328p. I am trying to set up a pin change interrupt and this is the code I am running. However, the interrupt never seems to trigger. ...
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36 views

Not able to set a value into an ADC

I'm trying to configure an ADC (ADC12j4000) and I need to configure the number of serial lanes (denoted as L in the page 39 of the datasheet). For some factors as D, DDR, P54, K... I can see how to ...
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1answer
3k views

Dinamically change PWM frequency with interrupt with STM32

i'm using an stm32f4 to control a stepper motor. I'm not sure if i need PWM mode or OC Mode or OnePulse Mode. I can generate a fixed frequency PWM wave but since i need a particular acceleration/...
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148 views

How to convert this ASM diagram to register transfer level?

So we have this ASM diagram, which I have to convert into register transfer level. I have already done some similar examples and I will usually start with defining next-state logic, than output ...
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42 views

How to find out a register contains inputs or outputs or both?

I don't have much experience with embedded systems and I am trying to check if is possible to determine if a register is made of inputs or outputs or a mix of inputs and outputs. Let's say I have a ...
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133 views

Datasheet register bit number

When it is written that to check if some flag bit is set, you have to look at for example 0x74[2], does that 2 means 3rd bit of register or 2nd? From which number they count in datasheet 0 or 1, how ...
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110 views

What are practical embedded system uses for each type of register configuration? [closed]

I'm interested in giving my students information about the following four types of registers in the context of microcontrollers and embedded system design. I am listing the uses (to my knowledge) of ...
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335 views

1 Bit Register out of D-type Flip-Flop

I am building a 1-bit register using a DFF: simulate this circuit – Schematic created using CircuitLab The problem I have is that I think it should be saving whether D is high or low when the ...
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2answers
156 views

Lithium button-cell battery discharging really quickly

I am working on a board with an ARM9 (SAM9X25). On this board there is a 3.3V lithium button-cell battery powering the VDDBU power rail. It is also used with a 100kOhm pull-up resistor for WKUP with a ...
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1answer
46 views

LIS331HH registers only returning zero

I am using the LIS331HH and the FRDM-K22F board. I can write to the power register and turn on the LIS331HH, I can also write to the interrupt control register (23h) and read out the value I've ...
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47 views

Having issues with clocking a 74S374 (D Flip Flop)

I'm having issues setting the state of any of the D Flip Flops, I have jumpers and a multimeter to work with. does the clock pulse have to more precise than touching the jumper to +5v? 74s374J data ...
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54 views

Modified ISA design

I want to represent 13 instructions, use 1 register operand and an immediate value that represent at least the number 1048576 (2^20). I have 94 general purpose registers and 32 bit instructions. Will ...
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2answers
91 views

What is the difference between a 74*374 and a 74*377

What is the exact difference between a 74*374 and a 74*377? The first is classified as an octal edge triggered d-type flipflop while the latter is an 8-bit register. I don't understand the difference ...
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1answer
416 views

Configure Serial with registers on STM32l073RZ

I'm trying to configure the Serial of my STM32L073RZ with registers to send datas on the PA_9 pin. Currently I have this script ...
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2answers
542 views

Manually storing the stack pointer rather than using push and pop (Assembly)

What will be the instruction sequence that implements PUSH R4? A: SUB SP, SP, #4 STR R4, [SP, #0] B: ...
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2answers
2k views

Which register holds the final arithmetic and logic results?

This Wikipedia page says an accumulator is a register in which intermediate arithmetic and logic results are stored. So which register holds the final result?
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257 views

Why does the STM32L4 ADC have a 12-bit SAR and 16-bit data register?

I'm working with the ADC on STM32L476RG. I found that the SAR used for the ADC is 12 bit whereas the data register (ADC regular Data Register (ADCx_DR)) is 16 bit (16 bit reserved). Why is it like ...
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1answer
611 views

Verilog register output: reg or wire?

If I want to model a simple register I would expect to have an internal 'reg' element to hold the value and I would connect this with a 'wire' output. The reg drives an internal output. However, I'...
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3answers
2k views

Does Registers and RAM are same kind of memory?

Recently, I found out a YT channel of a man who build a 8-bit computer and explain how. In his video on the registers, he uses a D flip-flop, and in his other video on the ram, I understood that he ...
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1answer
275 views

Confusion on pop for recursive assembly code

I'm confused on what happens during POP. When POP LR happens does that change the PC to the location of ...
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1answer
1k views

Confusion about ADR in ARM (assembly code)

I'm confused on what's happening with ADR R14,cnt1. Is cnt1 signifying the end of the program? And if so how will ...
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1answer
1k views

Reading data from register file in system verilog

I'm creating a simple register file in system verilog, with a total of 6 registers that can be written to/read from. When I run a simulation in ModelSim, the output never shows the correct data - it ...
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81 views

PAC1720 Standby Mode

I am having a hard time putting my PAC1720 into standby mode reliably. Here is the datasheet If I put the device in standby mode, then take it out of standby mode, and then try to put it in standby ...
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1answer
719 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
259 views

How to build PIPO register

Ive got problem with simulating 8-bit register. Ive built register using eight D flip - flop. Every flip-flop was made with 5 NAND gates + 2 NAND gates for Preset. My problem is that register doesnt ...
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3answers
2k views

How do registers work in a CPU? [closed]

Im going to build simple 4-bit cpu using only NAND gates and I have a couple of questions. How actually register work in cpu? For example: PC points to load instruction and CPU should store some ...
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1answer
2k views

Build A Two Port Write and Two Port Read Register File with 4 Registers

I am facing problem in my current task. I need to build a 2-port write and 2-port read register file with 4 registers. I am able to do the 2-port read part but I could not do the 2-port write part. ...
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4answers
648 views

Why is it required to use a register in the final stage output of a pipeline?

I'm following MIT 6.004x course, where in the pipeline section, it's stated that "our pipeline convention requires that every pipeline stage has a register on its output". I absolutely understand the ...
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170 views

Fibonacci LFSR - polynomial , sequence, phase shift

Hi, it's my first post here. I have a question according this picture. So let's see. IMHO the primitive polynomial for that LFSR will be \$x^4+x+1\$ but I'm not sure if I'm thinking good. I've read ...
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1answer
51 views

How to change the reading from an ADC of 10 bits to the timer 0 registers using a PIC18f4550?

I a reading an anlogue value using the 10 bits ADC from the Channel 0. I have implemented an interruption using timer 0, where I set some value for the registers of timer 0 (TMR0H and TMR0L - 8 bits) ...
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1answer
128 views

Z80 - adding numbers in U2 - settings of register flags

We have Z80. This processor do following operation in U2: 200 - (-56). What will be values of following register flags: S - the ...
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1answer
474 views

How to handle Register output in state machine with verilog

Assuming I wan't to implement a state machine in verilog, where I have 1 output which is a register So the output must be in sync with the input clock. I know that the transitions between the machine ...
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4answers
792 views

8-bit shift register 74LS164 not working

I am trying to use an SN74LS164 8-bit serial-to-parallel shift register with my Raspberry Pi, but I have some problems. I connected: VCC, A, B and CLR to +5V GND to 0V CLK to Raspberry Pi GPIO ...
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1answer
196 views

Orange Pi registers pointers list needed

I need the orange Pi lite registers mapping for a project but I can't find it anywhere. Does someone know the mapping of the registers?
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916 views

Does a signal need to be in a clocked process to be registered (VHDL)?

I understand that it is best practice to register the outputs of all modules; so, I want to do that. However, I'm unsure what exactly it means to register an output signal. I.e. Do I have to include ...
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339 views

Function of demultiplexers in Register File

What is the function of demultiplexers (DMX) in this Logisim diagram of a Register File design: Also could you explain the meaning of: dreg,sreg,treg dsel,ssel,tsel dwrite,swrite,twrite
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700 views

Register description PCF8574

I have problem with PCF8754 component. The PCF8754 is connected to stm32 MCU and PINS A2, A1, A0 are connected to GND. It means, that 7bit address is 0x20. I want read pin state(P0 to P7), and write ...
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2answers
181 views

Need understanding of the concept of word (memory)

I've been reading how memory works from a book. The problem is my weak english so I can't catch the meaning correctly. The text from the book : A computer with a 32-bit word has 4 bytes/word, ...