Merge pull request #127 from naksper/master

guide for how to upgrade if we do not have a dcard reader and a network interface working.

en/send files over UART.md

@@ -0,0 +1,60 @@
+# OpenIPC Wiki
+[Table of Content](../README.md)
+
+How to send files over UART
+---------------------------
+
+If SD card reader failt and there is no network configured on your cam, you may need to send a new firmware over UART interface to update the camera.
+
+## Sender:
+
+1- First we encode the files
+
+```bash
+base64 uImage > uImage.b
+```
+
+2- Now make sure your com send-file command is, ascii-xfr, this was my connection command line
+
+```bash
+picocom -f n -p n -d 8 -b 115200  --send-cmd "ascii-xfr -snv" /dev/ttyUSB0
+
+```
+
+Normally we want ascii-xfr on the receiving side, but since we don't have it, that -n works around this by maintaining correct line endings.
+
+
+
+## Receiver:
+
+3- Now that we've connected, go to the directory where you want the received file.
+```bash
+cd /tmp/
+```
+
+4- Start receiving the file by uart
+```bash
+cat > uImage.b
+```
+5- On picocom, I just CTRL+a+s, and enter the full path of the file I'm sending. Once the transfer completes, you'll need to CTRL+c to break that cat.
+
+6- Now we decode the file,
+```bash
+base64 -d uImage.b > uImage
+```
+
+7- Do whatever you can to verify that file is IDENTICAL to the one you sent, because an ASCII transfer has no checksum protection. 
+Openipc had sha512sum, but any checksum command would suffice. 
+
+
+```bash
+sha256sum uImage
+```
+Once you manually confirm the sums match, you can assume the transfer was successful!
+
+Repeat for rootfs steps 4,5 & 6, and now you will be able to upgrade with sysupgrade
+
+```bash
+sysupgrade --kernel=/tmp/uImage --rootfs=/tmp/rootfs.squashfs --force_ver -z
+```
+