Ethernet controller to transfer data from CCD cameras

Another application : to transfer data from CCD pixels toward a computer. In this case we upgraded a MAYA camera with the Embedded Ethernet Device (EED) board. We removed the Centronic EEP interface linked to the CCD camera microcontroller and install as a piggy back board our EED.

The "Old CCD MAYA camera controller" uses a PIC16C74 microcontroller, the Analog to Digital Converter (ADC) is a 14 bit AD679, convertion time is 8µs per pixel. This system used formely a centronic (printer port) EPP link , which obliges us to :
- Block all the PC interrupts during readout, preventing us using the camera with Operating Systems like WinNT or Windows 2000, blocks the master PC clock..
- Slow data transfer rate
- Length limited to 10 meters between PC and CCD camera
- Galvanic ground isolation was not possible, noise was increasing with cable length.

Here you can find the source file implemented into the microcontroller PIC16C74 v1.05, 08/10/2000

The EED was inserted to PIC16C74's bus. This PIC16C74 is now thru the FIFOs the SX52's slave. The Pic16C74 generates the clocks, trigs the ADC, get the 14 bits data and send it to a 16K FIFO. We had to re-make all the PIC16C74 software. This one is able to carry out the full CCD readout sequence including wiping, readout out data from any CCD window and any binning X and Y factor. The readout sequence has NO JITTER, because the Pic16C74 does everything whitout being interrupted neither by the PC nor by the SX52. The transfer speed limitation is now the ADC (8µs convertion time), not any more the one due to the EPP link. Our camera has an IP address (134.171.73.45) and can be "pinged" like any internet device.

"Ping" to the CCD camera

Image on top : EED (green PCB) installed on top to MAYA controller. Right, the 2x2K thomson TH7899M CCD.

A close up to the CCD, 28x28mm square photosensitive surface.

The two boards, one on top of the other, the white connector on top right is the ethernet cable going to a Hub. MAX333A chips are used to generate high and low rails CCD clocks.

CCD installed into the head.

One of the first bias image :

1 sec bias image segment of 500x930 pixels from a 2x2K CCD, hexibiting a readout noise is 14e- at speed of 10µs per pixel (100Kpx/sec). The bright pixels are hot pixels.

Before, to readout the whole CCD (binning1x1, 4 Mpixels), it took 75 sec, now it takes 40sec.

The speed limitation is due to the ADC (8µs convertion time) and the Pic16C74 microcontroller (200ns instruction cycle). Anyway, now we can use the camera with any Operationg System we want, at more than 100 meters appart. We feared about noise, but the noise figure is still the same,and even slightly better. No noise pattern is visible.

An image of M31, sum of 5 times one minute exposure, in front of 4 city lights......

So; it looks like that this is a SUCCES !!!!