DEPRECATED: 1/23/2000
DESIGN GOALS: I have talked about the IOP before so I will review the design:
- The IOP can control multiple CDUs (dumb terminals) via an Ardunio's USB.
- The IOP listens to the NavGroup UDP broadcast for present position, etc.
- The IOP sends the PP/etc to be updated on the CDUs.
- All software will be written in C.
- We will standardize on the eclipse platform for software development.
CDU - IOP Software Protocol:
- The CDU sends one character to the IOP. The IOP will respond with character string.
- The IOP sends a command to the CDU. The IOP will respond with NAC.
CDU - IOP Software Review: This IOP is built on on Linux platorm which performs the following functions:
- handles all input via an internal command select(2)
- All of the CDU's fuctions via a program called nav_iop.c
- The software handles all keystrokes
- The software handles the all the switches
- The software handles the displays
- As well as
- listening to the NAV-GROUP network
- Updating present position
- Storing all the variables.
- Multiple CDUs can be handled by using a array of structures to hold them.
- this is the definitions:
- enum fd_index {
- RD,
- WR,
- FD_pair };
- struct cdu_s {
// device info
char * device_info; // something useful about the cdu
char * device_name; // in the form of "dev/xxxxxxxxx"
int fd[ fd_index ]; // file descriptors
// power flags
int power;
int power_48v;
int power_400hz;
int keybord_power;
// keyboard state info
unsigned short alpha_high;
unsigned short alpha_low;
unsigned short clear_flag;
unsigned short keypad_power;
unsigned short cursor;
unsigned short keystroke;
// switch state info
unsigned short power_flag;
unsigned short mode_sw;
unsigned short display_sw;
unsigned short dest_thumb_sw;
unsigned short fly2_thumb_sw;
// display info
short display_cntl;
short keyboard_cntl;
char chars[displays][display_max + 1];
};
And this is how we invoke it.
static struct cdu_s cdu[] = {
{ "Pilots", "dev/USBtty0", {O_R, O_W }, } // Please note the the O_ option are for demonstration purposes only and are not correct.
};
ARDUINO Software Review: The Arduino has the following things to do:
- One Arduino per CDU so each CDU has its own Device Name ie /dev/USBTTY0. This is important, so that the NAV-IOP O/S knows which CDU is requesting service.
- Ps2 keyboard decoder, for the Keypad interface. There is a good article in the Arduino Playground.
- One 16 bit I2C Bus expander, PCF8575C,
- four switches (2 thumbwheel and 2 rotary).
- Drive two relays:
- Main Power
- Keyboard Lights
- Use two (2) MAX6955 Display Controlers via the I2C Bus, which drives the 16 and 7 segment displays.
| Processor Shoot Out | |||
|---|---|---|---|
| Devices | Pins | Duemilanove | Mega2560 |
| USB Serial Device | 2 | 0 (RX) and 1 (TX) | 0 (RX) and 1 (TX) |
| External Interrupts | 2 | 2 (INT0) and 3 (INT1) | 2 (INT0), 3 (INT1), 21 (INT2), 20 (INT3), 19 (INT4), 18 (INT5) |
| Ps2 Keyboard | 2 | 3 (INT1) and 4 (DATA) | 3 (INT1) and 4 (DATA) |
| I2C Interface | 2 | A4 (SDA) and A5 (SCL) | 20 (SDA) and 21 (SCL) |
| Display Switch* | 4 | N/A* | 22, 23, 24, 25 |
| Mode Switch* | 4 | 26, 27, 28, 29 | |
| Thumbwheel Switch 1* | 4 | 30, 31, 32, 33 | |
| Thumbwheel Switch 2* | 4 | 34, 35, 36, 37 | |
| Keyboard Power Relay | 1 | 38 | |
| Display Power | 1 | 39 | |
| MEM LED, Red | 1 | 40 | |
| MEM LED, Green | 1 | 41 | |
| MAL LED, Red | 1 | 42 | |
| MAL LED, Green | 1 | 43 | |
| Arduino LED | 1 | 13 (LED) | 13 (LED) |
*If the Duemilanove is used we need to use several I2C I/O Expander.
IOP (Linux) Software Review: The software is written using the Linux/Unix async communications with several devices (file handles) at the same time, that will include the USBtty, and UDP and TCIP connections at the same time.
(MORE TO COME)
Keep Tuned In More to Come!!
