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The Wifi Doogle

August 19, 2016, 1:01 pm

esp_doogle_shop

I picked up these neat little esp8266 USB dongles from Shenzhen. If you’re interested, I have some in my shop too.

They incorporate a CH340g, 3.3v voltage regulator and esp8266. This creates a complete stand alone esp8266 stick, so you no longer need a USB serial interface or external voltage regulator. Almost all the pins are broken out too, which makes hacking projects on it easy.

It uses the serial RTS and DTR lines to enable running or flash update modes. This is a bit odd, but it does mean that you don’t need to switch jumpers to change modes which is nice.

Startup board in normal mode, you need to execute the following in python:

import serial
ser = serial.Serial('/dev/ttyUSB0',9600)
ser.setDTR(False)
ser.setRTS(True)
ser.setRTS(False)

You can then read data using python with “ser.readline()”. If there’s interest in these boards I’ll write up some further notes on how to work with the board using minicom.

I also stripped one of the boards down, this might prove helpful with debugging. It certainly helped me better understand how the boot mode was selected:

wifi_doogle

A PNG is here. And a SVG you can load in Inkscape with the board sides aligned so you can follow traces is here.

For reference, here’s some of the information from the original Chinese seller:

esp_doogle_orig

 

esp_doogle_orig3

For reference, to start the board in flash mode you can use the following (esptool.py does this anyway):

ser = serial.Serial('/dev/ttyUSB0',9600)
ser.setDTR(False)
ser.setRTS(True)
ser.setDTR(True)
ser.setRTS(False)
Category: Uncategorized  |  Comment

awk – print text between 2 identical markers in a file

August 19, 2016, 1:04 am

Like this:

awk 'BEGIN{flag=0} /MARKER/{flag = !flag;next} flag' inputfule

Adapted from: here.

Category: Uncategorized  |  Comment

esp8266 SPI duplex transfers

August 18, 2016, 7:43 am

I’ve been working with the esp8266 spi driver by MetalPhreak located here. One of the issues I’ve found is that duplex transfers (where you want to both send and receive at the same time) don’t work correctly. If you attempt to call spi_transaction specifying 8 dout_bits and 8 din_bits 16 clocks will be sent (IIRC a receive followed by a transmit).

The misunderstanding is likely down to the fact that the esp8266 has very little documentation. And the SPI registers aren’t documented at all. However the Arduino guys seem to have figured it out and it works correctly in the Arduino IDE board pack for the esp8266.

The trick is to set the SPI_USER register just so. There are 3 bits which control the direction of transfer SPI_USR_MOSI, SPI_USR_MISO and SPI_DOUTDIN (bits 27,28 and 0). In order to send and receive you need to set SPI_DOUTDIN and SPI_USR_MOSI but NOT SPI_USR_MISO. At least that’s what’s worked for me.

I made the following modification to spi_transaction to fix this. Change the line reading:

if(din_bits) {SET_PERI_REG_MASK(SPI_USER(spi_no), SPI_USR_MISO);}

to

  if((din_bits) && (dout_bits)) {
    SET_PERI_REG_MASK(SPI_USER(spi_no), SPI_DOUTDIN);
  } else {
    if(din_bits) {SET_PERI_REG_MASK(SPI_USER(spi_no), SPI_USR_MISO);}
  }

I’ll probably submit a pull request once I’ve made all the changes required for my project. But in this meantime this should work.

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A git pre-commit hook to do SVN style $Date$ substitution

August 10, 2016, 4:29 pm

Put the following in .git/pre-commit (make sure it’s executable):

git diff --cached --name-only > commits_list

And the following in .git/post-commit:

#!/bin/bash

if [ -f commits_list ]
then
	currentdate=`date`

	cat commits_list | while read F
	do
 	 echo $PWD/$F
 	 filebase=`basename $F`
 	 sed -i -e 's/\$Date[^$]*\$/\$Date '"$currentdate"'\$/' $PWD/$F
 	 sed -i -e 's/\$Filename[^$]*\$/\$Filename '"$filebase"'\$/' $PWD/$F
	 git add $PWD/$F
	done 

	rm commits_list
	git commit --amend --no-verify -C HEAD

fi

Still not extensively tested…

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