doc: minimal parts list

README.md

@@ -106,6 +106,7 @@ with digital monitors/TVs
 Independent production
 like [q3k](https://twitter.com/q3k/status/1029010026269167618) is
 welcome and desirable under conditions of [modified MIT LICENSE](/LICENSE.md).
+If you do manual assembly here is [minimal parts list](/doc/MINIMAL.md).
 
 ZIP the gerbers and send them to manufacturer:
 

doc/MINIMAL.md

@@ -0,0 +1,42 @@
+# Minimal required parts
+
+When manually assembling boards, it is good to know
+the minimal parts list that has to be assembled for the
+board to respond and be programmed.
+
+FPGA
+
+    U1
+
+Switching power supplies:
+
+    C1,U3,L1,C2,RA1,RB1,C3,C4,C22,C17
+    C9,U4,L2,C10,RA2,RB2,C11,C12,C23,C19
+    C5,U5,L3,C6,RA3,RB3,C7,C8,C24,C20
+
+Power-up and hold circuit:
+
+    US1               - USB connector
+    D8                - US1 power routing diode
+    R10,D12           - USB power up
+    D16,R3,B0         - BTN0 power up
+    R6,Q1,D13,D10,R1  - power up transistor
+    D11,R4,R2         - power hold
+
+FPGA decoupling capacitors, board could probably
+work without them:
+
+    C17,C19,C20,C25,C26,C31,C32,C27,C28,C29,C30
+
+USB-serial to program FPGA over USB. FPGA can also
+be programmed without USB-serial chip using J4 JTAG header
+and external JTAG programmer:
+
+    R49,R50,R9,U6
+
+Clock 25MHz to properly clock examples.
+FPGA will respond with JTAG ID and can be
+programmed even work for combinatorial-only
+examples (no registers) without this clock.
+
+    Y1