drivers/sdcard: Add support for multi-block read/write; add SD test.

drivers/sdcard/sdtest.py

@@ -0,0 +1,57 @@
+# Test for sdcard block protocol
+# Peter hinch 30th Jan 2016
+import os, sdcard, pyb
+
+def sdtest():
+    sd = sdcard.SDCard(pyb.SPI(1), pyb.Pin.board.X21) # Compatible with PCB
+    pyb.mount(sd, '/fc')
+    print('Filesystem check')
+    print(os.listdir('/fc'))
+
+    line = 'abcdefghijklmnopqrstuvwxyz\n'
+    lines = line * 200 # 5400 chars
+    short = '1234567890\n'
+
+    fn = '/fc/rats.txt'
+    print()
+    print('Multiple block read/write')
+    with open(fn,'w') as f:
+        n = f.write(lines)
+        print(n, 'bytes written')
+        n = f.write(short)
+        print(n, 'bytes written')
+        n = f.write(lines)
+        print(n, 'bytes written')
+
+    with open(fn,'r') as f:
+        result1 = f.read()
+        print(len(result1), 'bytes read')
+
+    fn = '/fc/rats1.txt'
+    print()
+    print('Single block read/write')
+    with open(fn,'w') as f:
+        n = f.write(short) # one block
+        print(n, 'bytes written')
+
+    with open(fn,'r') as f:
+        result2 = f.read()
+        print(len(result2), 'bytes read')
+
+    pyb.mount(None, '/fc')
+
+    print()
+    print('Verifying data read back')
+    success = True
+    if result1 == ''.join((lines, short, lines)):
+        print('Large file Pass')
+    else:
+        print('Large file Fail')
+        success = False
+    if result2 == short:
+        print('Small file Pass')
+    else:
+        print('Small file Fail')
+        success = False
+    print()
+    print('Tests', 'passed' if success else 'failed')