Comparison

555 Calc vs AVR Tutorial

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

555 Calc

This utility app helps engineers and hobbyists calculate resistor values for circuits using the Timer IC 555. Simply input frequency, duty ratio, and capacitor values to get the required resistor outputs.

Highlights
  • Calculate resistor values
  • Input frequency
  • Input duty ratio
  • Input capacitor value
  • Timer IC 555 circuit design
Features
Read full description

This App calculates registors value, when designing the circuit using Timer IC 555. How to (1) Input Frequency value. (2) Input Duty Ratio. (3) Input C1 Value. (4) Touch ‘Calculate’ button. (5) Registors value will be displayed. Note. * Set Duty Ratio to 50 ~ 99. * If you set Duty Ratio to 50, R1 value will be set to 0.

About

AVR Tutorial

This app simplifies learning AVR microcontrollers with a code wizard that generates C source code for various peripherals. It offers demo projects and an architecture review, making complex MCU programming more accessible for hobbyists and students.

Highlights
  • AVR architecture review
  • AVR assembly and C language
  • 21 demo projects
  • Code wizard for peripherals
  • Portability to other ATMEGA MCUs
  • I2C and SPI EEPROM support (PRO)
Features
Read full description

This app is a AVR tutorial based on ATMEGA16 C language. It is suitable for hobbyist or engineering students. Learning AVR mcu is difficult. The learning curve is steep. The process including reading datasheet, writing code, building prototypes and troubleshooting. The most possible errors are the setting wrong value of registers. Now, AVR tutorial is the solution. The code wizard allow you to set the timer, UART, ADC, interrupt and peripherals by just a few clicks in setting. The proven C source code is generated automatically. Though the code wizard is based on ATMEGA16 mcu, it is easy to port to other ATMEGA mcu since the source code is highly structured Features • AVR architecture review • AVR asm mnemonics & C language • 21 demo projects including LED, buzzer, key switch, lcm16x2, ADC, etc • Code wizard for UART, timer, interrupt, ADC and external peripherals Features in PRO only • Support I2C eeprom 24C01 (128B) ~ 24C512 (64kB) • Support SPI eeprom 25010 (128B) ~ 25M02 (256kB) • Extra demo projects including led matrix 16x16, I2C eeprom, SPI eeprom • Code wizard for I2C eeprom, SPI eeprom, LCM128x64, etc Atmel® and AVR® are registered trademarks or trademarks of Atmel Corporation or its subsidiaries, in the US and/or other countries. This application is not related or affiliated in any way Atmel Corporation.

Screenshots

555 Calc1 screens
AVR Tutorial4 screens

Verdict

The call

The clearest difference is rating: AVR Tutorial at 5.0 against 555 Calc's 4.0. AVR Tutorial also leads on ads (none vs shown) and update cadence (every 3 months vs every 20 months). 555 Calc's advantage is in-app purchases (none vs 10). On price, ratings volume and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. AVR Tutorial sells 10 one-off in-app purchases. 555 Calc asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

AVR Tutorial holds the better App Store score, 5.0 against 4.0. Both are backed by a comparable volume of ratings — 3 and 2 respectively. Written reviews point the same way: 50% of 555 Calc's written reviews are positive against 75% of AVR Tutorial's.

UpkeepUpdate frequency

555 Calc ships an update every 20 months, AVR Tutorial every 3 months. The most recent releases landed on September 27, 2026 and September 24, 2026 respectively.

Scorecard7 real differences · 3 level
555 Calc versus AVR Tutorial: the parameters behind the verdict, then further details
Parameter555 CalcAVR Tutorial
PriceFreeFree
Rating4.0 (3 ratings)5.0 (2 ratings) — better
Positive reviews50.0% of reviews75.0% of reviews — better
Number of ratings3 — better2
Update frequencyEvery 20 monthsEvery 3 months — better
AdsYesNo — better
In-app purchasesNo — betterYes
MonetizationAd-supported — betterFree with in-app purchases
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS11.09.0 — better
Further details — not scored
Size18 MB33 MB
Age rating4+4+
DeveloperJibiki WorksSiu Yuen Ho

Customer experience

555 Calc

All ratings3 ratings
Positive66.7%
Neutral33.3%
Negative0.0%
Written reviews2 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

AVR Tutorial

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews4 reviews
Positive75.0%
Neutral0.0%
Negative25.0%

In-app purchases

None

555 Calc

No in-app purchases

10 purchases

AVR Tutorial

One-time10
  • Unlock PRO feature$1.99
  • SPI OLED$1.99
  • I2C OLED$1.99
Show 7 more
  • Wifi home automation$1.99
  • 2.2" TFT$1.99
  • LoRa home automation$1.99
  • Home automation using Siri$2.99
  • Home automation using Google$2.99
  • BT home automation$4.99
  • BLE home automation$4.99

Questions

Is 555 Calc free?
555 Calc is free to download, with no in-app purchases.
Is AVR Tutorial free?
AVR Tutorial is free to download, with in-app purchases available.
Which has better reviews, 555 Calc or AVR Tutorial?
AVR Tutorial is rated higher. 555 Calc averages 4.0 out of 5 from 3 ratings, while AVR Tutorial averages 5.0 from 2 ratings.
Do 555 Calc or AVR Tutorial have ads?
555 Calc shows ads; AVR Tutorial does not.
Which is updated more often, 555 Calc or AVR Tutorial?
555 Calc ships an update every 20 months, and AVR Tutorial every 3 months. Most recently, 555 Calc was updated on September 27, 2026 and AVR Tutorial on September 24, 2026.

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