Remote on for Raspberry Pi

This project is about to add a remote power on "switch" to a Raspberry Pi.
To switch the Pi on I use the connector "Run" on the board. If the two connections are shorted the Raspberry will power up. The plan is to use a BC547 transistor to short the pins. A ESP01 Wifi uC will control the transistor, make it conduct when a certain Mqtt-message has arrived.

ESP-01 "Al Cloud inside"

Bought some new ESP-01:s, the version with the black board labeled "Al cloud inside" (here. At first I tried to talk to it via Arduinos serial monitor, connected the Esp via a USB-adapter (here).

Tried some different settings in the serial monitor, what worked was 115200 baud, both NL & CR:





ESP01 as wireless programmer

Here we use a ESP-01 to program a Arduino.
The base is the Esp-link project,
I use a ESP-01 and connect it like this:
URXD: connect to TX of microcontroller
UTXD: connect to RX of microcontroller
GPIO0: connect to RESET of microcontroller

When using a 5V Arduino I use a resistor divider on the ESP:s RX as it's not 5 volt tolerant. 20k from Esp:s RX to ground, 10k to Arduino:s TX. No divider is needed on the ESP:s TX as it is an output.

Stiga Autoclip 140 / Ambrogio L50

Just some notes for now)

Connect to PC with HL-2303 cable. Use serial console (From Arduino IDE). 38400 baud.
The mower says:

Ambrogio Line50 Basic EUR
Board AM50 5.0
Built on May 24 2012 14:28:08
with r12947
Copyright (C) 2008 Zucchetti Centro Sistemi SPA

TEST A: Passed
TEST B: Passed

And repeats that.

Light sensing with a Raspberry Pi

In a project I wanted to measure the amount of light in the room for controlling the backlight of a Tft display. The project uses a Raspberry Pi, which sadly don't have any analog inputs. In this case one can use a Ldr or a photo transistor with a capacitor. The principle is that you set a pin as output and make it high. This charges the capacitor. You then set the pin as input and measure the time until the Pi consideres the input to be low. The time this takes depends on how much light the detector is exposed to and will be a value depending on how much light there is in the room.

Light controlled tea light

Electric tea lights are nice but they have a great disadvantage. There are small batteries in the base which dont last long and you have to replace them often. A modification is to remove the small batteries and add an external battery pack. The tea lights work on 3 volt, so two AA:s, rechargeable or not, will do.
I also tried to add a circuit that detects the light in the room and turns the light of at daytime, no need the have the candles lit then. The circuit is designed to draw as little power as possible, otherwise the gain of the power saving would be gone.

Measure light with an ESP01

The goal of this project is to measure the light level in a room and send the value to a web server. One difficulty here is the lack of an ADC-pin on the ESP01 that is used. This is solved by letting a capacitor discharge through an IR-transistor, an idea taken from Pololu.
You have to remove the connection to Gpio2 when uploading firmware.
For running in stand-alone mode, remove the connection to Gpio0.

Wireless relay board

The goal of this project is to build a unit with four relays that can be controlled via Wifi. The components are mainly a ESP-03 wireless module, a ready-built relayboard and a 3V3 regulator.


I start by flashing firmware found here.

Then I can use the Arduino IDE to program the ESP. Ch_pd is connected to Vcc and Gpio15 to ground. To program, Gpio0 is connected to ground while the power is cycled.

Arduino based AC remote

In the bedroom we have a portable AC to cool of the room. It creates some noice, and therefor we prefer
to run it at daytime and shut it off at bedtime. But how to remember to start the AC in the morning?
The AC has a remote controller, so the plan is to build a Arduino-based remote capable of imitating the stock remote.
The Arduino has a IR-transmitter and a RTC (Real Time Clock). In that way the Arduino can power on the AC
at a preset time and power off at bedtime.

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