MEGACAM - CFHT Telescope



MEGACAM CCD Controller block diagram (for 22 CCDs)

MEGACAM is the next generation wide-field camera to be used at the prime focus of the 3.6m CFHT telescope. This instrument, which will cover a full 1 square degree, is designed around a mosaic of 36 to 40 2Kx4K CCDs. Such a large detector requires new approaches for the hardware as well as the software, and will have major impacts on the telescope structure, optics and operations. MEGACAM will start operating in the year 2001.The camera will be designed and built at DAPNIA (Department d'Astrophysique, de Physique des Particules, de Physique Nucleaire et d'Instrumentation Associee), which is a division of the CEA (French Atomic Energy Commission).

The CFHT is the first telescope built on the Mauna Kea. Mauna Kea is the highest volcano of Hawaii (4200m). It is always above the clouds, far away from civilisation and is seen as the world's best astronomical site.

The total image containing 320 million pixels is 640 MByte. The readout requires two to four gigabit links for a readout time of less than 20 seconds.

The CCDs are connected to a SHARC DSP. SHARC to S-LINK logic will move the data to Motorola MVME processor boards running VxWorks with a commercially available S-LINK to PMC interface mounted on it. It is likely that in the final system the VME processor systems will be replaced by PCs with Linux.

The final readout system will be delivered in Summer 2001.



18 September 1998 S-LINK equipment (S-LINK to PMC interface, SLIDAS and FCS-LINK) acquired. 
SHARC to S-LINK interface logic being designed
9 July 1999 SHARC to S-LINK interface working. 40 MB/s without control words, 30 MB/s for 1 KB packets
12 July 1999 CERN sends one integrated FCS-LINK/PMC card to support the project. This card makes that the processor board with the S-LINK receiver on it takes up only one VME slot, instead of two.
24 September 1999 Ordered 8 FCS-LINK2 Link Source Cards
16 December 1999 S-LINK passed MegaCam Final Design Review. In January tests with FCS-LINK2 card will be made
6 April 2000 Hawaii group ordered two SLIDAS and two S-LINK to PCI cards


18 September 1998 VxWorks driver is under development. Based on LINUX S-LINK drivers from NA48 and ORL.
9 July 1999 VxWorks driver working. Tested on Motorola 2604-333MHz-64MB, with SLIDAS 82MB/s for 1KB packets
6 April 2000 Driver for receiving pixel data from imager on a PC with Redhat Linux 6.1 with a standard 2.2.14 kernel will be written by Hawaii group.
23 June 2000 Real-time Linux driver working.



CERN - High Speed Interconnect - S-LINK
Erik van der Bij - 17 October 2000