1. SCUBA-2 Systems Review Multi-Channel Electronics Hilo, Hawaii June 19-23, 2006

2. MCE Overview  Each MCE reads signals from a 41×32 pixel sub-array.  4 readout cards (RC) that each read 8 output lines through 14-bit 50MHz ADCs.  One address card (AC) that asserts each of 41 addresses at ~850kHz.  One clock card (CC) that interprets the commands and synchronizes all the cards.

3. MCE Interfaces

4. Synchronizer Box  Commands ? get_Status go enable DV-outputs st disable DV-outputs rt RTS mode (external DV supplied) fn n set frame num. to n fr n set free-run counter to n < 4095 nr n set num. of rows to n < 63 rl n set row_len to n < 4095 re reset ps power status dpa disable power for all 8 MCEs dpu n disable power for MCE(n)  Status Mancho_Enable = ON DV_Mode = FRUN_DV FRUN_COUNT = 47 row_len = 64 num_row = 41 ACDCCU_onoff = 0X00

5. Output of Synchronizer to MCE syncDVFr. No. 013339

6. SQ1 SQ2 SA_BIAS SA_OFFSET RCn A/D D/A PID SA_FB BC1 SQ2_BIAS (SB) BC3 SQ2_FB BC2 SQ1_BIAS (RS) AC 0.1 Ω 15 kΩ TES Bias BC2 ADC_OFFSET RCn SQ1_FB (110 Ω) data_mode 3: raw - data_mode 0: error data_mode 2:filtered 14b Dout + - data_mode 1:feedback LPF Cold ElectronicsWarm Electronics (MCE) A=195 2n2n 2m2m

7. Squid Characterization Using MCE  Sweep the feedback current of each stage across its full range and adjust the lower-stage feedback to keep the series-array output voltage constant. 1. Sweep Series-Array(SA) feedback Choose SA_BIAS, target voltage 2. Sweep SQ2 feedback and adjust SA feedback Choose SQ2_BIAS, SA_FB 3. Sweep SQ1 feedback and adjust SQ2 feedback Choose SQ1_BIAS, SQ2_FB, SQ1_FB 4. Turn on the servo loop 5. Sweep through TES_bias

8. bias and feedback for SQ1 and SQ2 are set to 0 Curves are near Ic max for all 8 channels Choose points at Maximum dV out /DI in

9. Squid characterization Using MCE  Linux shell scripts that call C functions to issue commands to MCE  Areas of improvement: Implementation in C RTL PC reliability: More reliable PCI card with additional diagnosis features More robust Operating System: e.g., Fedora Modular architecture (e.g., PCI Card driver independent of DRAMA and DAS)

10. Science Data Mode  In normal data mode the first-stage squid feedback signal, which is read at 20 kHz, is low-pass filtered and reported at every data valid pulse (DV), approximately at 200 Hz.  The filter is a 4-pole Butterworth filter with a cutoff frequency of ~50 Hz.  For each DV pulse, the MCE reports 41  8  4 32-bit values plus a header.

11. Engineering Readout Modes In addition to ‘Science Data Mode’ we have a number of readout modes to help diagnose performance.  Internal DV pulses up to 1.4 kHz. Normal format.  Combined Feedback and Error signals in 32b words  41×8 pixels sampled at 50 MHz, in a burst.  Reduced array area at a rate > 1.4 kHz  Error Signals only (ie not the Feedback signal) Combinations of these options are possible. Question: Can the Data Pipeline handle any of these?

12. MCE Power Shutdown MCE shuts itself down only if: Unacceptable high voltages/currents are detected. Unacceptable high temperatures inside the MCE are detected. MCE status prior to auto-shutdown is recorded into an EEPROM. AC/DC unit shuts down if over temperature is detected.