Cape v2.2 - PCB Changes

Implemented Changes

  • INFO for v2.1r0:

    • first 4 Target-Boards has green LED1 (down) and red LED2 (up)

    • Vanilla Shepherd v2.1 Cape stopped BB from booting and even putting it on while running failed (p8 41-44)

    • removed watchdogpins (pwrOn&reset) allowed to put cape on while running (still not while booting)

  • L3V-TestPosition is bad, easy to produce shorts with neighbour

  • update expected voltage levels in schematic

  • label for pwr-led

  • AB-label of target bigger

  • P7/P8 seems wrong name for big pinheaders

  • testpoints without paste, and small hole in copper to lock a probe ⇾ just less paste

  • is there a way for cage-selfalignment? ⇾ negative solder mask exp

  • remove layerwindows and make number bigger

  • describe external powering better in schematic

  • pin1 markings should be bigger

  • emulationBug! - Critical

    • solutionA - MinimalEffort: Swap FbB- with RailA-Trace

      • FbB ⇾ rotate R1/10k clockwise and attach it to middle pad

      • RailA ⇾ cut Trace between R9 and Via

      • connect enamel from R9 to (now) free Pad of R1 ⇾ this routes RailA to Switch

      • connect enamel from TP1-Pad to rotated R1 ⇾ this routes FbB to Switch

    • solutionB - clean: rewire output of AnalogSwitch

  • silk: vCap is now V_SimBuf

  • schem: recorder gain is now just 10

  • more Metal for cooling the recorder-Path

  • Rail-LED is twisted! ⇾ No its not

  • add 2x23 to BOM SSQ-123-03-G-D , digikey SAM1196-23-ND

  • VHarv lowpass is 160 kHz not 16 kHz as shown

  • change all lowpasses to 160 kHz

  • emulator should go back to 1 Ohm Shunt, 100 Ohms for InAmp for 100:1 Amp ⇾ now 2R & 1:50

  • Switch Ext-Pwr Pins (instincts are strong for edge-pin to be GND) and don’t forget Silkscreens!

  • EEPROM needs to be always powered (BB 3V3)

  • reduce V_IO_BUF OPAmp-Resistor to 10 Ohms

  • a little bit bigger 0402-pads, they get loose quiet fast

  • level-change performance is still bad! maybe add 1k back?

    • add back 1 kOhm as series resistor for LSF0801. maybe a bit lower because edges are a bit slow (1 us)

  • put a note in schematic for WD

    • BB_START has 5V Level when BB is on, gets pulled to 3V3 when WD does its routine because schematic uses BB3V on it. but that seems ok!

  • get target A/B/1/2 straight. it is target 1/2 from now on! ⇾ Skip it

  • C over Shunt is sometimes contraproductive (100 nF || 2 Ohm produce 1 MHz oscillation without any load but 100 nF buffer, 1uF/0uF is fine)

  • provide more help with switching to external pwr, switch? backside would be good

    • switch + jumper?

  • add 74HC4066 and OPA189 to consumer-list, build a low-pwr Overview

  • optimize shepherd-EN (unlink rec/emu?`, better buffering?)

  • hw may be glitching BB - caps are getting big, voltage drop also ⇾ critical!

    • maybe add lowpass to en-pin of regulators or limit power

    • TEST: run unittests 2-5x, often bb hangs itself somewhere between 47…80%

    • scope shows:

      • AC: 600mV dip on shepherd-enable, 3x 200mV stages, lowest point 600 us after start, then fast recovery to -300mV, slow after (quickshot 1-2)

      • DC: 800 - 1100 mV Dip, but the first one (after a break of some minutes) is more severe

    • another hang: converters did not start as planned, only 6V is up, L3V3 is at 2V, the others well below that

    • mitigations: 1mF/16V Cap on 5VBB reduces voltage drops to ~ 200mV (max 300), in a 5 ms Windows (quickshot 4)

  • Add Cap

  • run through hw_performance_v2.1r0 for final cross-check

  • allow to turn off ADCs (not that important for EMU-only)

  • maybe add 2nd Switch for PRU-Ports, or lower resistors to <= 100 Ohm (speed-improvement)

  • around switch-IC, avoid solder bridges per design even more ⇾ space out vias, reduce solder mask expansion

Additional Parts

Note: numbers for one Unit, refs are Mouser-Numbers

  • 2 Ohm precision shunt: 603-RT1206CRD072RL

  • 2 Ohm shunt: 667-ERJ-2GEJ2R0X

  • more 1k 0402 (2xRec, 2xEmu, 10x LvlChg)

  • 210R InAmp-Gain-Setter: 603-RT0402BRD07210RL

  • 1mF, 6V3, 647-UVR0J102MPD1TD (D8mm,L11mm,3.5mm Spacing)

  • analog switch, 2x 771-HC4066BQ115

  • 4x 963-NR3015T1R5N

  • LSF dev-kit

Open Issues

  • feducials could be removed - panel has plenty

  • more pinnumbers on big headers

  • test changed recorder

  • is harvest-LED working? YES, but only with higher currents

    • var1: bind to vsim to allow more refined feedback

    • var2: 3x 2.0V Leds from adc-input to -6V (with resistor, should always light up)

    • var3: v-to-i converter

  • switch to TI Version of LSF0801 ⇾ out of stock till feb.22

  • optimize LSF for 1 MBaud (see

  • WDog is still not triggering nSTART (pulse too short)

  • HC2G04 still has wrong comment

  • wrongly linked in schematic

    • C53 L3V is part of recorder, but should be open domain

    • C48 is recorder, but should be emu

    • C24 is open domain, but should be recoder

  • has DAC also pin to disable?