Raspberry Pi 4 is here!  

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Spyder
(@spyder)
Honorable Member
Joined: 10 months ago
Posts: 668
2019-09-03 6:59 pm  
Posted by: @sdey76

act like an access point ie rpi gives an acess point

One of the bots I'm testing is the Ubiquity, and while it does act like an access point, it won't connect to your phone until you actually start the rosbridge

roslaunch rosbridge_server rosbridge_websocket.launch

I decided that it would be easier to have both connections live, so I connected a cat5 as well as wifi. In fact, I also found it useful to have 2 or 3 telnet windows open for separate ros commands. You also need to issue...

roslaunch magni_demos simple_navigation.launch

For remote control. Mine, of course, doesn't work, and I'm pretty sure that it doesn't work cuz I've got the wrong motor controller because that's one thing I haven't yet found in the documentation... which motor controller to install

It's probably in there, I just missed it. It would be a helpful piece of information to have


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Ruedi
(@ruedi)
Active Member
Joined: 7 months ago
Posts: 7
2019-09-03 8:31 pm  
Posted by: @codecage

 

Don't know about a Pi 4 yet, just setting up a replacement that CanaKit sent since the first one never came up.  And guess what I have just discovered, but not 100% sure of what the real issue is, that indicates the first one may still have a chance?

hey friends,

first, my RP4 would not boot, and I discovered this hint on the Raspberry Pi Foundation website: (

Downloads

)

Recovery

If your Raspberry Pi 4 will not boot, it is possible that the SPI EEPROM has become corrupted.

To check, remove the SD card, disconnect the device from power, then reconnect it. If the green LED does not flash, you will need to reprogram the EEPROM:

  1. Download the bootloader
  2. Extract it to an empty FAT-formatted SD card and insert it into your Raspberry Pi 4
  3. Connect the power and wait for the green LED to flash quickly

 

OnceI had finished the above steps, my RP4 booted OK!


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codecage
(@codecage)
Member Admin
Joined: 10 months ago
Posts: 517
2019-09-03 8:48 pm  

@ruedi

I wish mine had been that simple!  I found and went through those steps but still no luck!

I did eventually get the Pi to display something on my Vizio D32hn-D0 TV/Monitor, but it involved fighting with the config.txt file in the /boot directory.  And I first had to use a TV/monitor that allowed me to see the RasPi setup screen in the first place (my main Sony TV in the living room).

What I haven't verified yet is that now that it works on my Vizio, will it still work on the Sony I used to get the initial setup done in the first place.

SteveG


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Ruedi
(@ruedi)
Active Member
Joined: 7 months ago
Posts: 7
2019-09-04 7:48 am  

@codecage

My apologies ... I was so astonished that I found the solution for my problem completely by accident. I had been considering to return my RP4 until I found this hint, and I was on this page for a completely different reason. From a perspective of the RP foundation, I think it is a recipe for customer disappointment to have people "discover" why their RP4 doesn't talk to them when it comes out of the box. 

Hmm, good luck with your problem, and I am sorry I couldn't help!


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codecage
(@codecage)
Member Admin
Joined: 10 months ago
Posts: 517
2019-09-04 10:09 am  

@ruedi

I totally agree with in respect to the bad customer reaction to their introduction of the RasPi 4.  With the new heat issues, what you ran into and the quite by accident that you discovered what the resolution to your issue was, and the same for my video issue.

The video issue didn't exist on any prior RasPi model, so why did they not maintain the same compatibility with the PasPi 4?  With the support of 4K video and a second video port added I guess they had to add something, but why mess up what already worked.  Looks like their Alpha and Beta testing left a lot to be desired.

SteveG


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Spyder
(@spyder)
Honorable Member
Joined: 10 months ago
Posts: 668
2019-09-04 6:40 pm  

Not sure if anybody cares about this, but, I'm working on making a Pi laptop sorta thing, so I needed to make sure that I could power the Pi4 on a battery...

And I can !

This is one of those 20,000mah power pack things. I think I paid $10 for it on Amazon. So far it's been running for about an hour with no lightening bolt and still 4 bars on the battery...

powerbank

Hmm. I wonder how long it will last if I just leave it

It's not doing anything tho. I think I'll just leave it idle to get a baseline for longest time up, then I'll try abusing it, and see how long that lasts. Oh, and the fan is taking it's power from the Pi also, so there's another drain to consider


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Spyder
(@spyder)
Honorable Member
Joined: 10 months ago
Posts: 668
2019-09-04 6:53 pm  

1.5 hours, and it's down to 3 bars with all stats steady...

pi@raspberrypi4:~ $ ./showstats.so
arm=896M
gpu=128M
temp=40.0'C
volt=0.8578V
frequency(48)=600169920

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Spyder
(@spyder)
Honorable Member
Joined: 10 months ago
Posts: 668
2019-09-04 8:12 pm  

Well, I was down in the shop, so I wasn't paying attention to it. The battery is dead

I'm gonna call it 2 hours (safely) That's not bad tho


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Spyder
(@spyder)
Honorable Member
Joined: 10 months ago
Posts: 668
2019-09-08 1:26 am  

Does anybody know if it's safe to power the Pi4 directly from the GPIO pins ?

I can do that on the pi3 and zero but I've only got the one Pi4 and I don't wanna ruin it


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teddy
(@teddy)
Eminent Member
Joined: 5 months ago
Posts: 34
2020-02-25 11:45 pm  

The reason I haven't bought the new Pi 4 is because of a "flaw" in the USB-C  Port.

It has been recognized and fix, along with some other issues.  Here is a Hack-A-Day Article on the Subject:

https://www.theregister.co.uk/2020/02/21/pi_4_fixed/

--

Also, BUY A FAN!  The Pi 4  runs WAY TO HOT, even when idle!

This post was modified 1 month ago by teddy

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