Stellar Observations Network Group (SONG): SONG in New Mexico

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=== Dome control ===

Dome control is implemented through software running on a Raspberry Pi. Initial implementation controls dome motors through the Autoscope box with Opto 22 relays, but goal would be to just control the dome relays directly. The Raspberry Pi has a RELAYPlates card with 7 relays, which control shutter direction, shutter power, dome direction, dome power, and watchdog reset. These relays connect the control lines to ground.

The dome encoder gets +5V and ground from the RPi, and receives 5VDC signals from the A and B phases of the quadrature encoder. These are wired into RPi GPIO ports through a level converter that converts 5V to 3.3V.
DC +5 and ground are connected to RPi power, A and B outputs are connected to level shifter input channels; level shifter output channels are connected to RPi GPIO pins.
| Encoder pin | function | D connector pin | D connector color | connect | level shifter wire color |
| 1 | +5VDC | 2 | red | RPi +5V   | |
| 2 | gnd | 8 | wht | RPi Gnd | |
| 3 | Bbar | 3 | |  | |
| 4 | B | 7 | vio |  level B2 | grn |
| 5 | Zbar | 5 | |  | |
| 6 | Z | 9 | |  | |
| 7 | Abar| 1 | |  | |
| 8 | A | 6 | blu |  level B1 | blu |

The home sensor gets +5VDC and ground from the RPi, and receives a signal on a GPIO port that is normally low, but goes high when the home magnet is in proximity to the sensor.S
| Sensor wire | function | circular connector pin | color | level shifter | color|
| | | 1 | wht | | |
| red | gnd | 2 | blk | RPi gnd | |
| blk | signal | 3 | brn | level B3 | gry |
| grn | +DC | 4 | red | RPi +5V | |

Low-level functions are implemented in the APOAshDome.py module. An ASCOM Alpaca interface was implemented using the templates from the [[https://github.com/ASCOMInitiative/AlpycaDevice|AlpycaDevice]] package.

Software is archived at [[https://github.com/holtzmanjon/APOAshDome]]

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