Saturday, January 24, 2015


Part II.b. Some technical hints regarding the hardware

Firstly we will speak a little about the Salvaged Satellite Receiver (SSR):
From the picture below you'll notice the main parts of the device:
  1. The power supply
  2. The front panel
  3. The SSR main board
The front panel of this model is a very simple one. It has 3 buttons (unused by me), an IR sensor, a 4 digit 7 elements LED display drived by an ordinary shift register (74 HC 164D) and 2 LEDs. Below you may see it:
Now, the interesting part is. We'll use the 4 digits LEDs to show the current time provided by the router through Arduino. Basically on the router is an application called each minute from crontab which deliver to Arduino the current time. Arduino catch the message and pass it to the front panel shift register to be displayed on the 4 digits 7 elements LEDs.
For this task I've used an Arduino Pro Mini 3,3V with an Ethernet card linked to the router's Ethernet port.
Note: Arduino use two type of Ethernet adapters. One is Ethernet Shield R3 which is used with 'Ethernet.h'library and the other is ENC28J60 Ethernet Module used with 'UIPEthernet.h' which is almost full compatible with 'Ethernet.h' library (in order to run examples written for 'Ethernet.h' you may modify the code line #include "Ethernet.h" with #include "UIPEthernet.h".
For ENC28J60 Ethernet Module there are also other libraries: 'etherShield.h', 'ETHER_28J60.h' (both used by me to receive data from router) and 'EtherCard.h'.
Ironically, with 'etherShield.h' I was able with ease to receive data, but unable to send data to router and with 'EtherCard.h' vice-versa (send data easy, but unable to receive data).
Fortunately, the IR Remote library prevent the proper usage of the shift register and forced me to use another Arduino for the remote control and another way to transfer the remote control codes (TP-LINK MR 3020 has only one single Ethernet port).
As you may see from the pictures below, Ethernet Shield R3 is bulky and expensive ($30-$35) and in conclusion ENC28J60 Ethernet Module is the most suitable for our project
Ethernet Shield R3ENC28J60 Ethernet Module

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