The Mux: Difference between revisions
m
no edit summary
mNo edit summary |
mNo edit summary |
||
| Line 93: | Line 93: | ||
The state of the Mux ICs in the rack unit is controlled via 3 lines: Chip Select (CS), Clock and data. Before communication with the ICs begins the CS must be cleared (active low). 64 bits of data must then be shifted into the the ICs (clock active rising edge) before setting CS to select the new inputs. The 32x4 Mux is generated using four 8x4 ICs with their outputs commoned together. Therefore the data is organised into four blocks of 16-bits, with each block controlling one of these ICs. For information on the order in which to clock in data, see the datasheet [[https://ystv.york.ac.uk/~documents/docs_resources/StationDocumentation/MAX458-MAX459.pdf]]. Importantly only one of the Mux ICs should ever be driving each output from the mux, with the outputs on the other three ICs all disabled. | The state of the Mux ICs in the rack unit is controlled via 3 lines: Chip Select (CS), Clock and data. Before communication with the ICs begins the CS must be cleared (active low). 64 bits of data must then be shifted into the the ICs (clock active rising edge) before setting CS to select the new inputs. The 32x4 Mux is generated using four 8x4 ICs with their outputs commoned together. Therefore the data is organised into four blocks of 16-bits, with each block controlling one of these ICs. For information on the order in which to clock in data, see the datasheet [[https://ystv.york.ac.uk/~documents/docs_resources/StationDocumentation/MAX458-MAX459.pdf]]. Importantly only one of the Mux ICs should ever be driving each output from the mux, with the outputs on the other three ICs all disabled. | ||
==Power supply== | |||
This is very much the weak point of the mux, and is tied up with why there are loads of unconnected BNCs on the back. | |||
There are two mains transformers: | |||
* 2x6V | |||
**50VA | |||
**powers + and - 5V rails | |||
*2x6V | |||
**3VA one | |||
**wired as 1x12V, 3VA to provide the +12V rail. | |||
All the supplies are smoothed with big electrolitics, and then regulated with 78/79 series regulators. | |||
All this is built on a length of chocolate block connectpr strip, with a lot of stranded hookup wire. | |||