January 24, 2015, 12:50 pm
A new version of the SDK was released today. A few additional APIs have been introduced, but it appears that no existing functions have been changed/removed. I was able to replace the 0.9.3 SDK with this and compile my codebase successfully. I’ll update here after I’ve tried flashing a device. (UPDATE: I tested the ADC code from yesterday with the new SDK and it worked well)
There are a few interesting additions, there appears to be a new API called smartconfig, it looks like this allows the device to be configured from a smartphone. The protocols used are called AirKiss and ESP-TOUCH. I had a quick look through the library symbols, there wasn’t anything new that jumped out at me.
UPDATE: I’ve left what’s written below for reference, but the esp-open-sdk is a better solution, you can see my notes of that here.
As part of the process of installing the new version of the SDK, I’ve been tidying up my toolchain a bit. A complete tarball of my setup is here. This is the Linux setup. To download an install it you should be able to do the following:
sudo su
cd /opt
wget http://41j.com/blog/wp-content/uploads/2015/01/Espressif.0.9.5.tar.gz
tar xvzf Espressif.0.9.5.tar.gz
ln -s Espressif ./Espressif.0.9.5
cd Espressif
#install the Xtensa compiler
git clone -b lx106 git://github.com/jcmvbkbc/crosstool-NG.git
cd crosstool-NG
./bootstrap && ./configure --prefix=`pwd` && make && make install
./ct-ng xtensa-lx106-elf
./ct-ng build
PATH=$PWD/builds/xtensa-lx106-elf/bin:$PATH
However I’ve not yet tried the above, if you are interesting in giving it ago please let me know. But these notes are currently for my reference. Once the SDK is installed, I used the following Makefile for building my projects Makefile. Here’s an example project I’ve been working on which uses this Makefile: bGeigieNano_ESP8266.tar
This is a continuation of my notes on the esp8266 microcontroller, you can find a complete list of my esp8266 posts here
January 24, 2015, 12:07 am
Olimex have made their esp8266 layout available here. It’s under a pretty permissive CC license (allowing commercial use with attribution). I’m interested in using this as a basis for my own designs. However Olumex use Eagle, and I’ve mostly using Kicad lately. This page contains image dumps of the schematic and layout for my reference in case I decide to use them as a basis for a Kicad design, I also generated the gerbers and attached them below.
Plug: I have a bunch of esp8266 related boards in my shop.
Gerbers using eagle (untested): espg.tar
The original Eagle file (also available on the Olimex site):
MOD-WIFI-ESP8266_eagle_sources
January 23, 2015, 8:45 pm
The esp8266 contains a 10bit ADC. There are apparently various issues, including instability when transmitting over Wifi, and the lack of a voltage reference. However it is usable. The analogue input is labeled “tout” on the pinout below:
Unfortunately this isn’t broken out on the cheapest esp8266 boards (the esp1) but it’s possible to get access to it with some wirewrap wire and careful soldering (see image above).
The ADC input can then be read using some relatively simple C code as shown below. This code was adapted from an old version of the SDK (it doesn’t seem to be present in the current version).
I’ve also attached a complete working example that uses the function below: adc_test.tar
uint16 ICACHE_FLASH_ATTR adc_read(void) {
uint8 i;
uint16 sar_dout, tout, sardata[8];
rom_i2c_writeReg_Mask(0x6C,2,0,5,5,1);
// disable interrupts?
SET_PERI_REG_MASK(0x60000D5C, 0x200000);
while (GET_PERI_REG_BITS(0x60000D50, 26, 24) > 0); //wait r_state == 0
sar_dout = 0;
CLEAR_PERI_REG_MASK(0x60000D50, 0x02); //force_en=0
SET_PERI_REG_MASK(0x60000D50, 0x02); //force_en=1
os_delay_us(2);
while (GET_PERI_REG_BITS(0x60000D50, 26, 24) > 0); //wait r_state == 0
read_sar_dout(sardata);
// Could this be averaging 8 readings? If anyone has any info please comment.
for (i = 0; i < 8; i++) {
sar_dout += sardata[i];
}
tout = (sar_dout + 8) >> 4; //tout is 10 bits fraction
// I assume this code re-enables interrupts
rom_i2c_writeReg_Mask(0x6C,2,0,5,5,1);
while (GET_PERI_REG_BITS(0x60000D50, 26, 24) > 0); //wait r_state == 0
CLEAR_PERI_REG_MASK(0x60000D5C, 0x200000);
SET_PERI_REG_MASK(0x60000D60, 0x1); //force_en=1
CLEAR_PERI_REG_MASK(0x60000D60, 0x1); //force_en=1
return tout; //tout is 10 bits fraction
}
UPDATE: There’s also a system_adc_read function in the library symbols, I’ve not used it but it could be worth looking at.
This is a continuation of my notes on the esp8266 microcontroller, you can find a complete list of my esp8266 posts here
January 23, 2015, 2:45 pm
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