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--- working_with_arietta [2021/09/16 15:30]
zwmm
+++ working_with_arietta [2022/02/12 22:48] (current)
zwmm
@@ Line 1: / Line 1: @@
 To expand the filesystem, if you installed a small-ish image, use
-''sudo growpart /dev/mmcblk0 2
+''sudo growpart /dev/mmcblk0 2''  # note there is a bug in some versions of growpart. https://launchpadlibrarian.net/481674848/growpart.patch
-sudo resize2fs /dev/mmcblk0p2''
+''sudo resize2fs /dev/mmcblk0p2''
 Reference on Acmesystem's website: https://www.acmesystems.it/download_roadrunner
+----
+''sudo stty -F /dev/ttyS0 115200''
+to speed up the console baud rate
 ----
 Booting from the out-of-the-box SD card brings up the wifi in access point mode, at IP address 192.168.4.1.
-To change the wifi connection to your LAN wifi, try putting these two commands in a set_wifi file, and execute the file:
+To change the wifi connection to be on your LAN wifi, try these two commands:
-''cat > set_wifi''
 ''nmcli con down hotspot''
@@ Line 16: / Line 18: @@
 ''nmcli dev wifi connect //your_ssid// password //your_password//''
-'' ctrl-D''
-then
-  bash set_wifi
-This might need to be done from a connected serial port terminal session.
+This has to be done from a connected serial port terminal session, since the first command drops the network.
+----
+Change the hostname!
+----
+Check wifi signal strength with:
+''sudo while sleep 1; do /sbin/iw dev wlan0 link | grep signal; done''
+This device is good for experimenting with long distance wi-fi: it has an RP-SMA(?) external antenna connector in addition to its PCB antenna. Here's a quick demonstration of the additional gain from my rough prototype of a 15 element Yagi antenna:
+<code>
+        signal: -57 dBm
+	signal: -59 dBm
+	signal: -55 dBm
+	signal: -57 dBm
+	signal: -55 dBm
+	signal: -55 dBm
+	signal: -53 dBm
+	signal: -49 dBm
+	signal: -51 dBm <-- switched to Yagi antenna
+	signal: -59 dBm
+	signal: -53 dBm
+	signal: -39 dBm
+	signal: -37 dBm
+	signal: -37 dBm
+	signal: -37 dBm
+	signal: -35 dBm
+	signal: -37 dBm
+</code>
+{{ :yagi.jpeg |}}
+----
+I upgraded to Debian Buster, added a couple of useful apps, and disabled some startup things from the original set up. Archive in tgz format of the /boot and "/" (root) partitions at https://drive.google.com/drive/folders/1jf0ftLS3ZI8OIi4vddLbEFxVNSIw8685.
+To use it:
+  * mount the SD card on another computer
+  * delete everything in both partitions or reformat (partition 1 is DOS format, at least 125 MB; partition 2 ext4, at least 3 GB)
+  * mount the SD card
+  * dearchive the root file system contents into the second partition //as root// (to ensure permissions get used), e.g.:
+  * ''cd /media/user/rootfs; sudo tar zxvf buster_files_systems.tgz rootfs''
+  * repeat for boot
+  * ''cd /media/user/boot; sudo tar zxvf buster_files_systems.tgz boot''
+  * run ''sync'' to make sure any file buffering is done
+  * umount the two partitions
+  * insert SD card into Arietta, and power it up!
+----
+porting Adafruit I2C library
+<code>
+acme@HEX-7E44:~$ diff /home/acme/.local/lib/python2.7/site-packages/Adafruit_GPIO/Platform.py Platform.py
+a23
+> import os
+a30
+> ARIETTA          = 4
+a39,41
+>
+>     if os.uname()[4] in ('armv5tejl'):
+>         return ARIETTA
+</code>
+and
+<code>
+acme@HEX-7E44:~$ diff /home/acme/.local/lib/python2.7/site-packages/Adafruit_GPIO/I2C.py I2C.py
+a54,56
+>     elif plat == Platform.ARIETTA:
+>         # Acmesystems Arietta can have multiple I2C buses, default to 0 (pin 12 SCL0 and pin 14 SDA0)
+>         return 0
+</code>
+----
+The are **three** I2C ports available on the Arietta. Their pinout is described at the [[https://www.acmesystems.it/i2c|Acme Systems website]]. I used a carrier board that did not have the grideye attached to extend I2C out to some pin headers, then did it on another populated carrier.
+{{ :i2c_extension.jpeg?400 |}}

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