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Project Apollo Beta 7.0 released!
http://nassp.sf.net/wiki/Installation
25068 Posts in 2094 Topics by 2266 Members
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Author Topic: Virtual AGS Development  (Read 2533 times)
eddievhfan1984
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« Reply #15 on: October 19, 2017, 05:08:34 PM »

So all it has to do is listen to the special data word that says "AGS update" and respond to the interrupt generated by that data word, right?
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rcflyinghokie
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« Reply #16 on: October 21, 2017, 06:07:08 PM »

Just wanted to share a few videos showcasing the AGS control of the LM Happy

Lunar ascent under full AGS control: https://youtu.be/uI38vocs5zQ

Lunar APS abort just after P64: https://youtu.be/0q8e5vb-dBo
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thewonderidiot
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« Reply #17 on: October 22, 2017, 12:30:41 AM »

So all it has to do is listen to the special data word that says "AGS update" and respond to the interrupt generated by that data word, right?

Yeah, pretty much. The AGS has an 18-bit input register that captures the first 18 bits of a 40-bit AGC downlink word. There's an additional discrete input for the Downlink End signal from the PCM, which sets a flip-flop. When the program detects that this input bit is set, it reads in the captured 18 bits. This read automatically clears the "end" flip-flop.

So in theory, all we need to do is read the downlink data out of the AGC, assemble the 18-bit word that the AGS is expecting and jam it into its input register, and then set a bit for it to know that it has data. I haven't looked, but aea_engine.c might need to be updated on the VirtualAGC side to automatically reset the end bit on input register read.
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rcflyinghokie
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« Reply #18 on: October 22, 2017, 08:08:00 AM »

Also FP8 has a separate downlink for RR updates using 18 bits so we need to be able to capture that downlink as well for FP8 missions.
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indy91
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« Reply #19 on: April 14, 2018, 11:35:58 AM »

The last remaining big feature of the AGS has now been implemented, PGNS to AGS downlink. Previously AGS state vector updates had to be done all manually, typing the data into the DEDA. Now Verb 47 of the LGC can be used to send the LGC state vectors of CSM and LM to the AEA. Should be much more convenient.
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