Good info, but if I am forced to use an older board such as an uno, nano, pro, etc then I tend to go the sprintf route as it doesn't require loading additional libraries and achieves the same thing. Bonus, the code works on pretty much anything(no outside library dependence that may not support your new MCU). And I know you mentioned that Serial.printf works on the ESP8266/32, but it also supported on a lot of the newer development boards out there as well (though your mileage may vary when trying to print floats/doubles). But as I mentioned earlier, if you stick with sprintf and Serial.print, I don't think you'll ever run into a system it fails on. It may be an extra line to print(over printf), but it is still far better than what you showed at the beginning of the video.

Thank you for taking the time and effort to create this tutorial.

Those who can read should check out the books... Although, the BBC series was quite faithful to the written work. If you understand floats, they work quite well. The computer uses binary -- not decimal -- so decimal values must be converted to binary before they are used/stored and the results must be converted back to decimal before printed. This is entirely different from calculators that use binary coded decimal (BCD). Only 24/32 bits are float precision; the other 8/32 bits are for the exponent. printf() has about 2 kBytes of program memory overhead, so for microcontrollers smaller than the ATMega328p, using that might limit your program size.

Another very informative video, as usual. Thanks Ralph!

Thanks Ralph. I'll be pointing my students to this video. Very well explained!

Ive used the sprintf in the past but i didnt know about the *. that is pretty interesting. Thank you for the video.

I use sprintf() a fair bit on both the Arduino and esp32. Didn't know I could use printf() on the esp32, but certainly will now. And I think I'd better download this arduino printf library too. You always teach me something new Ralph. Thank you Sir. Watching on my phone (as always).

Like your style. keep em coming ☺

Great walkthrough video as always 👍 Thanks for sharing your experience with all of us 👍😀

good vid, coming back to the atmel 2560 for 1 project after using the esp for years forgot about the printf not being included. Ended up using sprintf as a quick fix

Another great and very informative video, particularly with your earlier video on saving space with debugging statements.

Floats, when used properly, are accurate!

Oh, that's great Ralph, very informative really.

Ralph S. Bacon, a hoopy frood who knows where his towel is.

Surprisingly useful! Thanks for the tip Ralph 🤘🏻 (Watching on my phone 😉)

Thank you, very helpful.

The reason the original Arduino library omitted printf was the standard implementation is huge, and would consume an unfeasible amount of the ROM and RAM space on the ATMEGA324 used on the original arduinos. Marco's implementation is much smaller making it practical on an Uno. Of course, in reality most simple Arduino projects don't use much code space, so the convenience of printf may be warranted, especially while debugging. Its a lot easier to comment out a line or 2 of debug statements than huge blocks of code!

Who's not heard of The Hitchhikers Guide To The Galaxy? When I was on a trip to London in 1999, I managed to get the BBC radio play on cassette tapes :-) I had failed to find it in Norway, but was happy when I got it :-)

thanks for this very helpful video, test files and all other information stuff

Many thanks for this update. I am certainly going to take full advantage of 'printf' as you describe it in this video. I have always hated Arduino IDE for NOT including this feature. My last comment: your thumb had an "issue" which I assume hs been 'sorted'. Like the new video format you are using, too. UPDATE: Using VSC & PlatfromIO, I placed in my project folder's /lib folder, a folder /LibPrintf which has LibPrintf.cpp and LibPrintf.h. AND I had to include the /extras folder, too. So far this is brilliant and you 'prodding' has done the trick. However, when I had PlatformIO download and install the LibPrintf library in my project folder, it couldn't find the /extra folder it said. VERY CURIOUS!

Great work Ralph, I have been using printf since your video #168 where you introduced MCUdude minicore. He implements it natively in Serial so you can use Serial.printf(...) . What did you do to your thumb?

Very good explanation. Thank you. I just start using it and for me it seems better than serial.print. Btw, I watched using a cell phone 😀

Hey Ralph, congrats on another nice video. Since you're on the subject of Serial.print, Debug, printf, etc. you might be interested in this library: Streaming by Mikal Hart. I never write a program without it because instead of all those repetitive Serial.print statements, you can do this: Serial

Very useful stuff....cheers.

Another great video!!🤣 In the Specify_print_class the statement printf_init(Serial1). How or can you assign a second serial port?

The thing you mentioned about Floats and Doubles is really interesting... How would you go about measuring a simple voltage using an analog pin and not using a Float? Or are Floats only inaccurate when you are storing a number, and then want to recall that number on various occasions? Or have I misunderstood entirely!?

Thanks Ralph, you explain things really well. I have only just moved to PlatformIO. You seem to have a very clear Serial Monitor. Is this a PlatformIO extension and if so what is it?

At 15:24 you say %s is a C++ string but it is a actually a C string. C++ is happy with string objects and supports c strings only for backward compatibility. It is stated plainly on the page you referenced "Writes the C string pointed by format to the standard output (stdout)."

Great video. This library has proven to very useful in my projects. However I have 2 caveats for you viewers using PlaformIO. If one uses PlatformIO library manager to install this library, for some unexplained reason, the folder "Extras" which is referred in the LibPrintf .cpp and .h files, is not installed and therefore the project fails to compile. The solution is to download it from GitHub and manually install it. The second caveat is with the latest version of the library, V1.2.6. Although the library should use the Serial stream as its default, it does not. One has to initialize the printf object with the command "printf_init(Serial) in the setup function. Interestingly these "undocumented features" are not present when one uses the Arduino IDE. Thanks again for your great video.

Thanks Ralph! What program are you using for your serial monitor?

Very informative video Sir

Hi Ralph, here is a great Arduino function and worthy of a video. I wanted a simple way to generate 100ms and 1sec ticks for program timing, built-in timers can be used but not for any time of day code, as when they over flow and are reset there is no timer function taking place, so they become inaccurate over time. millis() is a none blocking ms counter and counts from reset up to about 50 days before rolling over. Example use, counter = millis() / 100 to get 100 ms or counter = millis() / 1000 for seconds count. Virtually any timer can be defined in code and with my Arduino nano_connect (rpi PICO) it keeps perfect time over many weeks, so negating use of RTC in some instances.

Thanks, great tip again. When I try to combine this tip with the previous one on removing the serial.prints with the debugger to speed-up everything there is an issue with the number of arguments that is always different. Is there a workaround for that?

Thanks Ralph, I’m familiar with and have used pointers for a long time in C but haven’t seen references like this before. Are they a C++ only thing?

A nice video informative and I can see you are getting fed up with the serial.print function in your previous programming:-) did the lid drop on your Thumb:-)

Best thing before sliced bread? Cornish pasty?

Hey Ralph, Not another of them dang coding vids.. Hehe all good, i enjoy them all.

please try the Ayu theme for VC

Can you use FlashStringHelper with printf? Otherwise I could see sram usage going up if you can't put your strings into flash using FSH.

Thank you for explaining the use of printf, this function seems to have more powerful formatting capabilities than Serial.print, I will try it next time I need to print with an Arduino. However, I disagree with you on two points : First, I personaly don't like long printf lines (nor any long lines) in code. It is more difficult to understand what happens than with many short lines, and more difficult to modify, should you change someting later on. If one gets too many lines of code, one can always write a new function to move them elsewhere. Second, I think floating point are marvelous, provided you understand what precision they have. Arduino has only single precision, therfore it is normal that you obtain a 6 to 7 digits accuracy for you PI representation! The error was in your expectation, not in the way the number was represented ;-)

alternately, without having to include a library: char pout[250] = {}; // at the top of your code, globally. // later in your code sprintf(pout, "Iteration %i has a value of %li (derived from %6.10f)", intValue, longValue, floatValue); Serial.println(pout); The length of your line is limited to the size of the pout array (250 chars).

these "Advanced" / alternative coding videos are a great idea any chance of doing them on a regular basis? maybe drop them in inbetween projects?

Which is more performant in terns of ram/stack space, program space and execution speed in very small (tiny) memory footprint Arduinos?

how about a video about not using floats? I made a solar power monitoring system and needed to use floats for Wh calculations. Is it easier to not use floats?

It would be useful if I can 1-shot snprintf the names of enums too like with booleans and %s

correct me if I'm wrong. I remember using a command called " Serial.printf(); " which works similar to printf in c. what's so different between that command and this library?

I like the tidyness of printf over serial print, but Im not happy about giving up 1/3 of my memory for it. According to the library readme file, if memory footprint is critical, you can disable features; "For Arduino IDE, the flags need to be added to the compiler.extra_flags property in platform.txt or platform.local.txt". I found the file, but its not obvious in what way I need to edit it to disable the features Im not using or how much memory Ill be able to save. Anyone able to help?

Why not LibPrintf? (which is in the libraries list) backslash n : -works slash n : /n -won't

Any use of this to impose output formatting to LCD?

👍 great video

I am fairly noob myself and I am using Serial.print and Serial.println still... To make it fit into a single line of code, I simply use the String() function which in this case would equate to: Serial.println("Iteration " + String(intValue) + " has a value of " + String(lintValue) + " (Derived from " + String(floatValue) + ")"); I admit it's not as elegant as the printf() function, but it does work in the Tinkercad simulator whilst printf() doesn't.

AH! found a SOLUTION! Yes a buffering issue. I can use fflush(stdout); after the printf statements that don't have on them that works with my ESP32 dev board. reading in C++ reference there is also the option for setvbuf but I don't pretend to understand that one! both methods can cause performance issues but for my simple test sketch fflush is fine! Hi Ralph, Oddity with the escape sequence! I'm running a small sketch with a matrix keypad on and ESP32 dev board. keypad all works fine so I had a go with printf (native to ESP32 so no library involved) My code displays keypress to the console without the and a counter sends a after every 5 keypress's. Problem is nothing appears on the serial monitor or cool-term until the 5th keypress. unlike your last example in the video. Seems to be an issue with the native ESP32 implementation not flushing to console output until a is issued. How do I do that? and ideas?

This works perfectly fine w/o external libs (real copy-paste from my TM1640 display for lab PSU): float voltage, current, power; static char sprintfBuffer[16]; static char voltageChar[7], currentChar[7], powerChar[8]; dtostrf(voltage, 6, 3, voltageChar); dtostrf(current, 6, 3, currentChar); dtostrf(power, 7, 3, powerChar); sprintf(sprintfBuffer, "%s%s%s", voltageChar, currentChar, powerChar); Serial.println(sprintfBuffer); display.println(sprintfBuffer);

If you want Serial.print() to print PI to 8 places use Serial.print(PI,8), the printf library uses too much space (~10K) on a Nano/Uno which is what most beginners will be using. BTW l is a length specifier for printf not a long type it promotes the i or d (signed decimal integer) to the length of a long integer.

Is the %i %li and %f order of declarations critical. Like if you had %i and %i

Can you not use the standard (cstdio) C++ libraries in Arduino?

At about 12:04 you say that that the value of Pi is "garbled". What actually happened is there are rounding errors. When a number is stored in a variable it is converted to a binary representation of the number. When it is converted back to a decimal string representation for printing there is typically a rounding error. You can get a value closer to what you are expecting if you employ some rounding and truncate off a couple of the least significant digits. There is no floating point unit in a simple microprocessor so floating point operations are much slower than integer operations. This is the more typical reason for avoiding floats where possible.

The best thing before sliced bread was and still is oven baked bread.

Dear Ralph, thank you for your explanation of printf(). However, I do not understand how you derived 1000000 from 3.1415926 after 42 iterations.

max baud rate for arduino not 9600 ? thx

I do MOST of my UKposts viewing on my phone. Some on my laptop. And some on the 50” tv in the lounge.👍 But I must correct you on your hhgttg…. 42 is not ‘the meaning of life’. It’s only a number. 42 is the answer to the great question of life, the universe and everything. The biggest supercomputer ever know, called Deep Thought , was built to calculate the answer to that question. And it came up with the disappointing result of ‘42’. So the planet builders of Magrathea were contracted to build an even more powerful computer, called The Earth, to calculate what the actual question was. Unfortunately, moments before it completed its computation it was unexpectedly demolished to make way for a hyperspace bypass.

I feel lack of response to unasked question: how much does libprintf cost? I mean - just beggining Serial does cost around 1kb of space. How about this library?

that library alone eats up 38% of my nano program space

Uhm, working with Perl for so long time and entering Arduino world made me feel that Arduino is so neutered from usual tools that i used to use xD I understand lack of foreach() as Arduino "flavor" of C bases on, well, C. But ommiting something as basic, as taken for granted, as (s)printf gave me that feeling that i probably chose wrong hobby xD I am still a begginer on Arduino, yet i have this feeling that next wall i will painfully hit will be strftime or something similary "granted" by standard library ;p

OK great to not use floats, providing they are constant. If you consider something like a macro rail that mathmatically keeps track of the camera mathmatically. To move 4 mm 12800 steps need to be taken. I want the system to move to 12.895mm, and then take a shot every 0.02mm in the opostire direction for 4.68mm. So with that a step size of 0.0003125mm calculate the number of steps neede to get to the starting postion, the number between shots and the number of steps for the diseried 4.68mm. Or I could put in the total distance i want it to cover and the number of shot and have it calulate everything else. The further to to that the system hase to do thing like calculate depth of feild, feild size and image overlap via a percentage. These are going to making very heavy use of floats as it's hard to find a way of multiplying (x10,000,000 would be the smallest possible solution -this wil cause issue when counting longer distances) out for every possible iteration and would most likely take up as much time and space as using an exteranl FPU (better yet use a chip that has one). Floating point rounding error is very well documented and every digital adding device has the same issue. I am 100% certian that the error that you get from it isn't going to effect any arduino project enough for it to be an issue - it's why they don't use them for protien folding! Honestly saying they are inacurate is like saying you don't trust your phone, your calcuator, your car, your microwave, your camera... you get the picture. It's not an issue until you get to a serious level of computing, way, way beyound what anyone will be doing with something as small as an arduino or other microcotrollers. It is also impossible to store the exact number of pi - it's an irrational number as we have not found an end to it. A float to 15dp is way more than good enough. Then the number such as 10/3, will never be accurate as we, as humans, will just round it at some point. It has no end, it repeats indefinitely. The only issue is the understanding of what is required, and what is not. Accuracy to 30dp, not normally required, for most cases 4-8dp is enough and arduino software floating point is capable of that Also Serail.print(float, Number of decimal places); //this is day one arduino stuff

maybe the trick of using an empty comment block at the end of a code block works in arduino, example end with a pure /* */ and then when you need to block the the code above it just need to add a /* at the beginning of your code block, the whole /* ...... /* */ is now a comment, the second /* is ignored. no need to delete the /* */ each time.

😍😍😍😄

Meanwhile, the entire audio software industry uses floats just fine.

Or else: sprintf to a character array, then println that array. No xtra library needed.

(disclaimert: I know you are trying not to lose beginners here, but I can't resist) With the advent of calculators we've lost the understanding of significant digits. When people calculated by hand they knew better and stopped when more didgits didn't make the answer better. In this case pi would be 3, because while 42 has 2 significant digits, 1000000 only has one. I may have that slightly wrong as I got a poor grade on the significant digits section in maths class. plus among my friends the more digits of pi you can recite the greater your status. I guess I am saying float and double have their place. 11/3

42 isn't the meaning of life, the universe and everything. It's what you get when you multiply 6 by 9.

That ("\") is not a slash. It's a backslash. This is a slash: /

Using printf since the 1980s....

Hey Ralph, nice thumb. Please do tell us how we can get one of our own. By the way, another excellent video. Thanks.

"once you'll do you'll never forget to do it" (about putting a ). Yea, also Perl taught me that every print(f) end with , also end of sentence is not a dot but semicolon; ;)

8-bit Mega's are great for starting out, but there are the Teensy series that use Cortex CPU's that will blow the Mega out of the water With FLOPS. Serial.print(floatValue, 8); should print the float value to 7 digits including the whole number. What would be really interesting is to get printf or print to output as scientific exponential eg: 4.7e-6 But you're not crazy enough to do astrophysics on a 8-bit micro with no FPU clocked at a sloww 16MHz struggling doing single precision float math at ~78uS/op. On any Mega (328,2560) a double is 4 bytes as is a long and is at best 2x slower than int (2bytes) math. Raspberry Pi's can do double precision, have division units, and are clocked from 500..2000+MHz. So C language operations are a LOT faster on something like a Pi or Teensy (also clocked from 60..600MHz).

FYI Ralph PI is declared as a global variable in the Arduino.h header so you can use it, as well as: #define PI 3.1415926535897932384626433832795 #define HALF_PI 1.5707963267948966192313216916398 #define TWO_PI 6.283185307179586476925286766559 #define DEG_TO_RAD 0.017453292519943295769236907684886 #define RAD_TO_DEG 57.295779513082320876798154814105