B4R Question ESP32 (WROOM) - Could a kind soul please assist


Well-Known Member
Licensed User
So, I came across this From this posting

And, bear with me, from my no knowledge viewpoint I wanted to unpack what this all means . . .
Well, I think I have it, but am worried that if I misinterpret the explanation I would kill the ESP32 unit

For the ESP32-DevKitC, to flash programs from development environments, like Arduino IDE or B4R 1.8.0 (or higher).
Example B4R IDE:
* Pin IO0 (= GPIO0) to Ground * Compile and upload. Wait till message "waiting for download" in the B4R IDE Log Tab appears.
* Pin IO0 (= GPIO0) NOT to Ground
* Press BOOT button and hold down
* Press EN button (enable) and hold down
* Release BOOT button
* Release EN button

Above there are two parts, it would seem. I've done one in underline and the other in bold.

The bold matches what I had read and found has to be used for compile/upload to ESP32 (read it some time ago).

Its "header" is * Pin IO0 (= GPIO0) NOT to Ground

Then : The underlined one has the "header" * Pin IO0 (= GPIO0) to Ground

Question is : What does (=GPIO0) to ground? mean physically?

It looks like -> if this (GPIo0) is connected to ground then one does not have to do the BOOT / EN hold bit and it will write to the ESP32. I then presume that the bits in BOLD fall away and you don't have to do the BOOT/EN hold part anymore (not using B4R so even after the "waiting for download" appears doesn't come into it for me).

I've never seen that suggestion anywhere in the more formal Arduino fora. It seems to be saying loop a wire from GPIo0 to the GND rail. Not going to do that until some Guru can say that's right Dumbo. And, the B4R thing is irrelevant in the context I suppose, because, well, it wouldn't matter what IDE one is using, surely, its a physical connection. Which can go POEF..... {{Ahg >> anyway this is there at the top like Arduino IDE or B4R 1.8.0}}

The bit in bold above is a right PitB


Licensed User
Cray X-MP
Close but no cigar! - It's hard to tell them apart but I believe this may be Cray-1 Serial Number 1, the first one built and currently in the Chippewa Falls museum .

Hanging over it is this sign which, when you blow it up, seems to identify it as 'Cray-1 S/N 1'

cray1 sign.jpg
Upvote 0


Licensed User
Further to the above, if it is S/N 1 then it is probably the actual machine that was at Daresbury Laboratories in the UK from 11th May 1979 to 16th October1980.

From a thread here from a long time ago (2010)
linum said:
the image you use for your avatar. It looks pretty cool but, what is it?
The most iconic, and probably the most famous, supercomputer ever built, the Cray-1.
Seymour Cray once said that Cray weren't so much computer designers as refrigeration engineers. The bench seats house the power supplies, not the cooling as some descriptions have it. The cooling was a massive installation much bigger than the machine and was located out of sight away from the computer room. The Cray software research centre in Minnesota was built without heating - in winter they used the waste heat output from their Cray-1 machines to heat the building.

It was roughly organised as a set of bit planes vertically, so it was literally 64 bits high! The propagation delay of electrical signals (5 nanoseconds per metre in copper) was a limitation on the machines' speed as it had a cycle time of 12.5 nS. Op-code execution rippled circularly round the machine and as it could overlap operations several "wavefronts" could be circulating at the same time.

linum said: Wow! Very impressive. Have you ever had a chance to get your hands on it?
I've walked round one and chatted to the resident Cray-1 engineer about the machine.

Long ago (1978!) the Science and Engineering Research Council at Daresbury Laboratories near here aqcuired a Cray-1 from (I think) the Met Office to analyse data from (mainly) crystalography experiments on the beamlines of their X-ray synchrotron.

I had just joined a startup electronics firm that did instrumentation work for Daresbury and my first job was to design some custom commmunication hardware so that a bank of about 20 PDP11 16 bit minicomputers could collect data from around the accelerator. They fed it to two Interdata 32 bit superminis which in turn fed an IBM360 mainframe that organised storage and fed a Cray1 supercomputer. Awesome system for its' day but your top-end PC probably has more grunt now than that lot combined!

Daresbury Laboratories had a village hall sized room that was originally the disk farm for the 360 with load of 3030 removable disks for storage. On occasional visits over the years I saw this room empty as drive technology improved until the storage consisted of a single 6' high 19 inch rack of optical drives.

JesseW said: Some guys get to have all the fun!!!

The previous eight years were probably more fun. :) Working for Ferranti designing and building training simulators for the Royal Navy using early germanium transistor Ferranti Argus machines and their later silicon based successors.

These were BIG cutting-edge engineering projects simulating the sonar, radar, control and weapons systems of anti-submarine frigates, anti-submarine helipcopters and tactical and strategic nuclear submarines. I never got to play with anything remotely that expensive again.
Upvote 0


Licensed User
Cray-1 Serial Number 1, the first one built and currently in the Chippewa Falls museum.
IF YOU JUST VISIT THE museum’s website it would seem as though the Chippewa Falls Museum of Industry and Technology is trying to hide the fact that they have the most extensive collection of Cray supercomputers and related artifacts in the world. This hidden gem has every Cray supercomputer ever made in its collection, including Control Data machines designed by Seymour Cray.
I've added that to my list of places to visit next time (if ever again) I'm in the USA. 🍻
Upvote 0


Licensed User
Further to the above, if it is S/N 1 then it is probably the actual machine that was at Daresbury Laboratories in the UK from 11th May 1979 to 16th October 1980.

Hey, looks like you're right. I doubted that a computer in the UK would return to the US, but... apparently it would (I guess because it's #1)

Upvote 0