Wall drawing robots

Drawbot Overview:

www.marginallyclever.com/2012/02/drawbot-overview

This is the “grandfather” of all these wall drawing robots:

http://juerglehni.com/works/hektor/

The ChalkBot also is a good source of information:

https://blog.hipolabs.com/chalkbot-77a312921dd0

Giant Drawing Machine:

https://essay.utwente.nl/73003/1/te_voortwis_janwillem_BA_EEMCS.pdf

Make Arduino XY Plotter Drawing Robot Polargraph:

https://www.hackster.io/mertarduino/make-arduino-xy-plotter-drawing-robot-polargraph-b4fe36

How to make an OpenSource Vertical Plotter:

https://www.open-electronics.org/how-to-make-an-opensource-vertical-plotter/

Der Kritzler:

https://tinkerlog.com/2011/09/02/der-kritzler/

Software to help develop PCB Antennas

This is a small list of open-source software to help develop antennas:

openEMS:

http://openems.de/start/index.php

NEC2++:

https://github.com/tmolteno/necpp

Angora:

http://angorafdtd.org/

Microstrip Patch Antenna Calculator:

http://www.emtalk.com/mpacalc.php

Update: Presentation about openEMS: https://archive.fosdem.org/2019/schedule/event/openems/attachments/slides/3367/export/events/attachments/openems/slides/3367/openEMS_FOSDEM19.pdf

Converting graphic to data

Very useful web tool:

https://apps.automeris.io/wpd/

Practical understanding of key accelerometer specifications

This is a document TP328 from Endevco:

https://ia601502.us.archive.org/25/items/18109924/18109924.pdf

IEEE-754 Floating Point Converter

This is nice for debugging purpose, when you are seeing printf %f printing wrong thing:

https://www.h-schmidt.net/FloatConverter/IEEE754.html

Just print the float value as hexadecimal using printf %x to confirm it is equal to value you saw in the above link.

Using GSM Modem on NuttX with DNS support

I already demonstrated how to use NuttX with GSM modem. But I realized that it wasn’t with DNS support enabled. Then I decided to enable DNS and test it again:

 ATE1
 OK
 chat: OK AT+CGDCONT=1,"IP","tim.br"

 AT+QACCM=0,0
 OK
 chat: OK ATD99**1#

 AT+CGDCONT=1,"IP","tim.br"
 OK
 chat: CONNECT 
 ATD99**1#
 CONNECT
 IP: 192.168.254.254 
 IP: 100.86.71.207 IP: 100.86.71.207 

nsh> mount -t procfs /proc
nsh> ifconfig
ppp0    Link encap:TUN at UP
        inet addr:100.86.71.207 DRaddr:192.168.254.254 Mask:0.0.0.0

nsh> ?
help usage:  help [-v] []

[         cp        exec      hexdump   mh        set       umount    
  ?         cmp       exit      ifconfig  mount     sh        unset     
  addroute  date      false     kill      mw        sleep     usleep    
  break     dd        free      ls        nslookup  test      xd        
  cat       echo      help      mb        ps        true      

Builtin Apps:
  ping        testlogbuf  leds        pppd        

nsh> nslookup google.com
Host: google.com  IPv4 Addr: 172.217.29.110

nsh> ping google.com
PING 172.217.29.110 56 bytes of data
56 bytes from 172.217.29.110: icmp_seq=0 time=420 ms
56 bytes from 172.217.29.110: icmp_seq=1 time=490 ms
56 bytes from 172.217.29.110: icmp_seq=2 time=530 ms
56 bytes from 172.217.29.110: icmp_seq=3 time=840 ms
56 bytes from 172.217.29.110: icmp_seq=4 time=410 ms
56 bytes from 172.217.29.110: icmp_seq=5 time=500 ms
56 bytes from 172.217.29.110: icmp_seq=6 time=540 ms
56 bytes from 172.217.29.110: icmp_seq=7 time=590 ms
56 bytes from 172.217.29.110: icmp_seq=8 time=640 ms
56 bytes from 172.217.29.110: icmp_seq=9 time=680 ms
10 packets transmitted, 10 received, 0% packet loss, time 10100 ms
nsh> 

I just followed the video tutorial #044:

Ping on NuttX returning EALREADY

After the GSM modem connection I’m trying to “ping 8.8.8.8” and it is returning an error:

 ATZ
 OK
 chat: cmd 1, arg ON
 chat: cmd 4, arg 30
 chat:  ATE1
 chat: OK AT+QACCM=0,0
 ATE1
 OK
 chat: OK AT+CGDCONT=1,"IP","tim.br"
 AT+QACCM=0,0
 OK
 chat: OK ATD99**1#
 AT+CGDCONT=1,"IP","tim.br"
 OK
 chat: CONNECT 
 ATD99**1#
 CONNECT
 IP: 192.168.254.254 
 IP: 100.74.7.202 
 IP: 100.74.7.202 
 nsh> ifconfig
 nsh: ifconfig: opendir failed: 20
 nsh> mount -t procfs /proc
 nsh> free
              total       used       free    largest
 Umem:        24416      15016       9400       9400
 nsh> ifconfig
 ppp0    Link encap:TUN at UP
         inet addr:100.74.7.202 DRaddr:192.168.254.254 Mask:0.0.0.0
 nsh> ping 8.8.8.8
 PING 8.8.8.8 56 bytes of data
 No response from 8.8.8.8: icmp_seq=0 time=1000 ms
 No response from 8.8.8.8: icmp_seq=1 time=1000 ms
 No response from 8.8.8.8: icmp_seq=2 time=1000 ms
 No response from 8.8.8.8: icmp_seq=3 time=1000 ms
 No response from 8.8.8.8: icmp_seq=4 time=1000 ms
 No response from 8.8.8.8: icmp_seq=5 time=1000 ms
 No response from 8.8.8.8: icmp_seq=6 time=1000 ms
 ERROR: sendto failed at seqno 7: 114
 7 packets transmitted, 0 received, 100% packet loss, time 7070 ms
 nsh>

I suspect the issue is in the Mobile Operator TIM

UPDATE: I was using a bad antenna. Using a better GSM antenna everything worked fine: