mbv: now with DDR! and a wozmon

We have access to 256 MiB of fresh DDR3.
Isn't that great?

prog.py is a bit opinionated for now:
- tty is /dev/ttyUSB1
- writing programs to DDR

mbv/prog.py

@@ -0,0 +1,57 @@
+import serial
+import struct
+import sys
+import time
+
+offset = 0x80000000
+tty = '/dev/ttyUSB1'
+baud = 115200
+chunksize = 128
+
+
+def write(s, offset, dat):
+    for i in range(0, len(dat), chunksize):
+        chunk = dat[i: i + chunksize]
+        cmd = struct.pack('<cII', b'c', offset + i, len(chunk))
+
+        print(f'Sending {len(chunk)} bytes @0x{offset + i:04x}')
+
+        s.write(cmd)
+        s.write(chunk)
+
+        ack = s.read(2)
+        if len(ack) < 2:
+            raise RuntimeError(f'timeout waiting for full ack. got {ack}')
+        if ack[0] != b'a'[0]:
+            raise RuntimeError(f'expected ack, got this instead: {ack}')
+        print(f'Ack! len={ack[1]}')
+
+
+def jump(s, offset):
+        cmd = struct.pack('<cI', b'j', offset)
+        s.write(cmd)
+
+
+def main():
+    binfile = sys.argv[1]
+    with open(binfile, 'rb') as f:
+        dat = f.read()
+
+    s = serial.Serial(tty, baud, timeout=1)
+    write(s, offset, dat)
+    jump(s, offset)
+    last_dat = time.time()
+
+    while True:
+        dat = s.read()
+        if not dat:
+            if time.time() - last_dat > 1.0:
+                print('Data timeout')
+                break
+            continue
+        last_dat = time.time()
+        sys.stdout.buffer.write(dat)
+
+
+if __name__ == "__main__":
+    main()