Tests-Protocol for Capes

Visual Inspection

Look for tombstones, shorts, missing components and parts with wrong rotation (diodes, ICs)

It’s beneficial to take macro-shots of the untouched PCBs for later reference as it is hard to determine error causes once the PCBs are fully assembled, encased and deployed.

Isolated Cape-PCB

  • apply external power to PCB directly (current limited 5V via lab supply)

  • initial consumption < 1 mA

  • Pull Up EN_Shepherd (P8-13) with 3V3

    • consumption on 5V rises to ~71 mA

    • Power-LED below recorder should light up

  • check generated voltages on board (marked at capacitors by silkscreen)

Name

Expected Voltage

Comment

L5V

5.000 V

Should be Spot On

A5V

5.000 V

Should be Spot On (is L5V with pi-filter)

L3V3

3.300 V

Should be Spot On

6V

5.38 V

[5.29; 5.47] V with 1% Res

10V

9.73 V

[9.56; 9.90] V with 1% Res

-6V

-6 V

[5.94; 6.06] V with 1% Res

Cape-PCB on BeagleBone, powered

  • BB starts 390 mA on VDD-5V line, booted: 170-240 mA

  • sudden 66 mA increase on shepherd EN is no problem for BB

  • WD-Pins could be a problem - my current test-BB is sensitive for power-button and shuts down ⇾ use jumper?

  • P8-43 or 44 is sensitive for input - BB does not boot when shepherd connects with these pins

    • both are for boot-config, BUT

    • LA shows that both pins are high even before 3v3 gets to the pins, lasts 7.4s for a fresh BB

      • P8-45/46 stay low during boot an later on

      • p8-41/42 are HIGH for the same 7.5 s on boot

  • EN-Shepherd (P8-13) stays low during boot - perfect!

  • a fresh BB is sensitive for boot-pin during operation, it will shut down! start by triggering boot-pin again. Reset does nothing during power-off

    • boot is high even before power-up. then low 2.3s until 3v3 come to pin ⇾ shutdown command (short low), but then stays high during power-off

      • react to shutdown seem to be controlled by software (important for watchdog)

    • reset is low, changes to high when 3v3 come to pin, when 3v3 go on shutdown, the pin also changes to low

  • GPIO to target

    • GPIO 0 - 4 are working bidirectional

    • BATOK is always high (currently), pru-debug-answer shows it

    • uarx (target - right) shows 1.5V, TODO

    • urtx (target - legt) shows 3V, TODO

    • swdIO is inversed? low for 80ms instead of 10 ms high, or something is pulling

    • swdCLK is fine

  • Noise from Outside (v2.0r1)

    • BB 5V Lines (both) show cutting 1V transients every 23.6 ms, around 400 us long (quickshot 73/74/80) ⇾ due to diode between both 5V-Lines

    • entry-filtering is not doing much for these rails

    • 6V has +120/-80 mV Spikes (qs77, 78)

    • 5V and 6V are only used as intermediate voltage steps

    • 10V +46/-30 mV

    • -6V +42/-30 mV

    • A5V +36/-28

    • 36 us, +-10mV Spikes, 500 ns long (qs82, 84)

    • ⇾ add a big external Cap on 5V

    • diode-connection between the two 5V-Rails could be the problem - there are no voltage-spikes over the diode, so the current seemed to be constant

      • without diode: Big Spikes are gone, 5V has now max -200 mV and other (qs85)

      • -6V & 10v & A5V are cleaner, delta 30mV (qs86-88)

    • a Cap, 1F 5V5, before the ferrites, does not improve the situation

  • Performance (v2.0r1):

    • 0 to 5V Target A, with 1 kOhm Load, 75 us for 80%, ~100 us for 100% (QS92 & 94)

    • 5V to 0V T-A, …., 75 us for 80%, 400 us for 100%?, qs93

    • Recorder is following, with 5V in, 1k pre-resistor, the op-amp switches from 0..5V with 20us period, shape of thin half sine

      • big voltage jumps take 1 to 1.7 ms, 0 to 5V, that’s also the period duration for no active load

  • Performance (v2.1r0)

Current PCB-Mods (v2.0r1): - P8-43/44 disconnected, messes with boot - P9-9/10 possible problem, unconnected for now - 2x 10k-PU from EMU/REC EN routed to 3V3 (easy) instead of 5V, ADCs still work - 2x 1k-PU for boot, reset pins, only on shep-pcb als external jumper - switched inputs of R13, Shunt of Recorder, 2 lines cut and rerouted - diode over reverse-pol-mosfet - 1k for LEDs ⇾ OK - 1 Level Translator fixed (single supply & lower threshold voltage ~ 900 mV) - (NO!) 5V_SYS switched over to 5V_VDD - 8 Ohm right before Shunt ⇾ stabilize

Current PCB-Mods (v2.1r0):

  • switched target-power-lines between OP-Amp and switch

  • 1 mF / 16 V Cap on 5V PCB-Input ⇾ helps stability during shepherd-enable

  • change R15 (V_harv_sim), R8 (emu-rail_b) from 10k to 1k to bring lowpass to 160 kHz (6us) instead of 16 kHz (62us)

  • incomplete list, see “44_hw_performance_v2.1r0”