Put in some meaningful files

Mostly documentation, still not the actual schematics

README.md

@@ -1,2 +1,61 @@
 # Zest
-Zest is a FMC mezzanine board with 6 ADC channels and 2 DACs
+
+This directory will hold the schematics and associated files (but not the layout)
+for the the Zest board, an FMC-ish mezzanine board designed for LLRF and related applications.
+Before its release as Open Hardware, it was known as the LCLS-II LLRF Digitizer Board, currently Rev. 1.1.
+It is in gschem format; to work with it you
+need [gschem](http://wiki.geda-project.org/geda:gaf) installed.
+Tested on [Debian](https://www.debian.org) Jessie, Stretch, or Buster, where
+you simply `apt-get install geda-gschem`.
+
+![Image of completed board](doc/digitizer_top_x.jpg) [block diagram](doc/digitizer_block.png)
+
+The digitizer board features:
+
+* 8 x transformer-coupled inputs sampled at 95 MS/s (2 x AD9653)
+* 2 x transformer-coupled outputs sampled at 190 MS/s (AD9781)
+* Input clock source up to 3 GHz (LMK01801, no on-board oscillator)
+* Extra clock divider output
+* 2 x Pmod digital I/O
+* Interface to FPGA via dual-LPC-FMC connectors
+* 181.8 x 110 mm, 8-layer, with notch to accommodate Xilinx FMC eval boards
+* 4W power dissipation
+
+## Schematics
+
+To get PDF versions for reference,
+simply `make` in this directory.  The result is digitizer_schematics.pdf.
+
+## Artwork/Gerbers
+
+Created by Kathy Pham at SLAC using PADS.  Latest is 20170519.
+The PADS design imports the netlist exported from this gschem design.
+These PADS files are _not_ kept in this git repository, but
+their SHA256 signatures are kept in the
+[layout_20170519.sha256sum](layout_20170519.sha256sum) file in this directory.
+
+QR-code serial-number overlay Gerbers are generated with `qr_gen.py`.
+
+## BOM
+
+Get a copy of the `PC-379-396-15-C02_DIGITIZER BOARD_XY.xlsx` file exported from
+the PADS design reference above, and place it in this directory.
+
+Then `make merged_xy.csv` to merge the actual orderable part numbers (kept here
+in the parts.data file) and get a usable xy assembly file for fabrication.
+
+## Plastic Cover
+
+One corner of the digitizer (by J3, clock input) has some fragile transformers
+very close to where SMA wrenches are used.
+It has proved helpful to have a protective cover in place to avoid damage.
+This is designed in [OpenSCAD](http://www.openscad.org/) with a process that
+matches up its features with the Gerber file; see covergen.py.
+The OpenSCAD source file is cover1.scad.
+OpenSCAD will export an STL file which is easily 3-D printed.
+
+## References
+
+ G. Huang, L. R. Doolittle, J. Yang, Y. Xu,
+*``Low Noise Digitizer Design for LCLS-II LLRF,''* in NAPAC2016
+[TUPOA40](http://accelconf.web.cern.ch/AccelConf/napac2016/papers/tupoa40.pdf).

cover1.scad

@@ -0,0 +1,45 @@
+/* Digitizer cover to protect its transformers near J3 and J20 */
+/* Obsolete, see cover2c.scad */
+/* See also covergen.py */
+
+/* 5 mm from board to attached SMA connector, which still fits in */
+/* the 7.9 mm cutout for the board-mount SMA connector. */
+/* 7 mm from board to the beginning of the hex section. */
+/* Part is 5.5 mm thick, to avoid slight interference with SMA connectors found with a 6mm thick version. */
+
+module cover()
+{
+  union() {
+    difference() {
+       union () {
+          translate([0, -39.5, 2]) cube([40.5, 39.5, 3.5]);
+          /* copper pad on board measures 5.8 mm dia */
+          translate([37.55,-36.5, 0]) cylinder(r=2.9, h=4, $fn=30);
+       }
+       union () {
+          /* 106.3 mil = 2.7 mm dia hole, tight clearance for 4-40 */
+          translate([37.55, -36.5, -1]) cylinder(r=1.5, h=8, $fn=30);
+          translate([ -1, -11.50, 0]) cube([10.6, 7.7, 8]);  /* J3  */
+          translate([ -1, -26.75, 0]) cube([10.6, 7.7, 8]);  /* J20 */
+          translate([ -1, -42.00, 0]) cube([10.6, 7.7, 8]);  /* J11 */
+          /* TCM4-19 datasheet claims max height 4.06 mm, I measure 3.1 mm */
+          translate([11.3, -15.2, 0]) cube([4.2, 4, 4.0]);  /* U34 */
+          translate([17.3, -15.2, 0]) cube([4.2, 4, 4.0]);  /* T1 */
+          translate([11.3, -26.0, 0]) cube([4.2, 4, 4.0]);  /* T1 */
+          translate([39, -24, 1]) mirror(v=[1, 0, 0]) linear_extrude(height = 1.5) {
+              text("LBNL", size = 6.2, font = "Liberation Sans");
+          }
+          translate([28, -34, 1]) mirror(v=[1, 0, 0]) linear_extrude(height = 1.5) {
+              text("R3", size = 6.2, font = "Liberation Sans");
+          }
+       }
+    }
+    /* these are the stubs supposed to rest on the bare board */
+    translate([0,    -3.6, 0]) cube([ 9.5, 3.6, 2]);
+    translate([0,   -18.2, 0]) cube([ 9.5, 3.6, 2]);
+    translate([0,   -33.1, 0]) cube([16.0, 5.2, 2]);
+    translate([25.3, -6.1, 0]) cube([ 9.5, 6.1, 2]);
+  }
+}
+
+cover();

layout_20170519.sha256sum

@@ -0,0 +1,4 @@
+6cbed80c2a59994bd1079787402c8bbd41b0e4aac596df6ae13ff0d52cd22452  PC-379-396-15-C02_DIGITIZER BOARD_GERBER.zip
+41695319dbba6b2a0f070e53f15aa4e91d6cd02aab0c0f8df19309e846284ad0  PC-379-396-15-C02_DIGITIZER BOARD.pcb
+755974be8790143d8e31a287eb366f4e4facb41aa9633fdf04591ec5c7711a8d  PC-379-396-15-C02_DIGITIZER BOARD_XY.xlsx
+e4acd72a8bf70de439603d0e74e5d18f4af4e1b64bf01f2c5adaf508655656ea  PC-379-396-15-C02_DIGITIZER SA TOP.pdf

qr_gen.py

@@ -0,0 +1,91 @@
+import numpy
+import qrtools
+import scipy.ndimage
+import os
+
+def qrpng2pcbpoly(qrpngfilename, x0=9600, y0=3200):
+	im = scipy.ndimage.imread(qrpngfilename, flatten=True)
+	ymax, xmax = im.shape
+	y, x = numpy.where(im == 255)
+	x0 = x0 - 450
+	y0 = y0 + 430
+	step = 14
+	polygons = []
+	for ix, xvalue in enumerate(x):
+		x1 = x0+xvalue*step
+		x2 = x0+xvalue*step+step
+		y1 = y0-(ymax-y[ix])*step
+		y2 = y0-(ymax-y[ix])*step+step
+		polygons.append('''    Polygon("clearpoly")
+	(
+		[%.2fmil %.2fmil] [%.2fmil %.2fmil] [%.2fmil %.2fmil] [%.2fmil %.2fmil]
+	)''' % (x1, y1, x2, y1, x2, y2, x1, y2))
+	return '\n'.join(polygons)
+
+# String length limits for Version 2 (25x25), assuming "Alphanumeric" encoding:
+#  level='S'   40
+#  level='M'   28
+#  level='Q'   22
+def qrgen(string, level='M'):
+	print("qrgen: " + string)
+	qr = qrtools.QR(string, pixel_size=1, margin_size=2, level=level)
+	qr.encode(string)
+	return string+'.png'
+
+def pcbstring(x, y, size, s):
+	return '''
+	Text[%3.2fmil %3.2fmil 0 %d "%s" "clearline"]''' % (x, y, size, s)
+
+def pcbstrings(l):
+	return "".join([pcbstring(*ll) for ll in l])
+
+def munge_size(l, xmax, ymax):
+	if l[0:7] == 'PCB["" ':
+		return 'PCB["" %.2fmil %.2fmil]' % (xmax, ymax)
+	else:
+		return l
+
+def get_template(xmax=12000, ymax=10000):
+	with open("template.pcb", "r") as f:
+		template = f.read()
+	lines = template.split('\n')
+	return "\n".join([munge_size(l, xmax=xmax, ymax=ymax) for l in lines])
+
+
+def pcbfile(silk, template):
+	return template + '''Layer(10 "top silk" "silk")
+(
+'''+silk+'''
+)'''
+
+def infopcb(lines, sn, x0=9600, y0=3200):
+	line_break = lines.split('\n')
+	return pcbstrings([
+		(x0, y0+0, 110, line_break[0]),
+		(x0, y0+70, 110, line_break[1]),
+		(x0, y0+140, 110, line_break[2]),
+		(x0, y0+210, 200, 'S'),
+		(x0, y0+320, 200, 'N'),
+		(x0+100, y0+180, 500, '%03d' % sn)])
+
+def oneboard(gerber_name="a.gbr", sn=1, qr_string="TEST 1", desc_string="", x0=3900, y0=1200, level="M", template="", lines=""):
+	polys = qrpng2pcbpoly(qrgen(qr_string, level=level), x0=x0, y0=y0)
+	pcbstr = pcbfile(silk=infopcb(lines, sn, x0=x0, y0=y0)+polys, template=template)
+	pcb_name = 'test'
+	with open(pcb_name+'.pcb', 'w') as f:
+		f.write(pcbstr)
+		f.close()
+	os.system('pcb -x gerber %s.pcb && mv %s.%s.gbr %s' % (pcb_name, pcb_name, 'topsilk', gerber_name))
+
+
+if __name__ == "__main__":
+	setup = [3900, 7450, 'qr_sn_%03d.gbr', 'LBNL DIGITIZER V1.1 SN %03d', 'M', 'LBNL Digitizer\nLCLS-II LLRF\nRevision 1.1']
+	# setup = [10000, 5360, 'qr_dn_sn_%03d.gbr', 'FNAL DOWNCVT REV C SN %03d', 'M', 'FNAL DOWNCVT\nLCLS-II LLRF\nRev C']
+	# setup = [6900, 2300, 'qr_up_sn_%03d.gbr', 'FNAL UPCVT REV C SN %03d', 'M', 'FNAL UPCVT\nLCLS-II LLRF\nRev C']
+	x0, y0, gerber_base, qr_base, level, lines = setup
+	template = get_template(xmax=x0+1000, ymax=y0+1000)
+	for sn in range(32, 57):
+		gerber_name = gerber_base % sn
+		qr_string = qr_base % sn
+		desc_string = ''
+		oneboard(gerber_name=gerber_name, sn=sn, qr_string=qr_string, desc_string=desc_string, x0=x0, y0=0, level=level, template=template, lines=lines)