In this Blog Post, I will carry on with phase I of testing. This consists of four (4) components. The radio head itself, which has not been modified. The Custom Cable consists of 2 DB-25m connected to 3 ARINC connectors. The RSS C-3436A interface. And lastly, a python script running on my Linux box to talk to the radio head via a USB cable just for testing.
The testing will have several major objectives:
- The out of frequency indexes for MHz and KHz are working.
- Make sure that I can retrieve the correct frequency for Mhz.
- The KHz is a simple matter it is just 10 times the index.
- That I can see the power switch's state (ON, OFF)
- (Optionally) and can turn on the front panel lights via the Hv relay.
The slave pictured below (orange picture) has an Arduino its 2 DB25F connectors, an integration power connector DIM-5, a dual RJ-45 breakout board, and the CANbus module, the single-channel power relay has not been installed at this date.
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// this typedef subs byte for a // unsigned char typedef unsigned char byte;
typedef struct assignments { byte nodeID; byte dataType; // UCHAR byte serviceCode; // xCHAR byte canID[3] = {$450x}; byte message[4]l byte } devices; |
If this all works the next stage is to integrate this with the CANbus using CANaerospace protocol formats. One of the first things that I will have to do is write the heartbeat or IDS on Node Service 0.This makes sure that a CANaerospace network can be scanned for attached units to determine their status, header type, and identifier assignment. Note that within a CANaerospace network, other header types than the standard CANaerospace header and several identifier assignment schemes (including entirely user-defined ones) are supported. Whenever possible, it is strongly recommended to use the proposed standard header and identifier assignment,
For the devices, I will have to construct a structure to hold all of the info, here which you can find here on pages 15 - 45 this radio: has a CAN identifier of 1104 The Suggested Data Type is a Float (32 bits 1 sign bit, 23-bit fraction and 8-bit exponent according to IEEE-744-1985 or ACRHAR4, and its units are in MHz. Now going back to page 7 where you see that ACRHAR4 is 4xASCII chars.
Since the CanAerospace Data package is 8-Bytes, I will create a new Data Type 4xhex chars. So the maximum for the high side is 126 decimal which is 7Exhex, which will go into byte-7. The maximum for the low side is 9 which is 09xhex, which will go into byte-6. That leaves me bytes 4 and 5 for switches etc.
| Node-ID | Data-Type | Service-Code | Message-Code | Data | |||
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|
| 450 | 64 | 2 | 09 | 7E | |||
| 450 | 64 | 1 | 1 | ||||
This device will use a custom Data Type 4xHex | 64xhex
The NodeID assignment is 450x ie page 43 CANaerospace Interface Specification
This is the response for status.
bit 0 is for the power 1::=ON. 0::=OFF
bit 1 is for the lamps
This is the lamp command.
bit 1 is for the lamps
