Improved error handling for set_v and set_i

Now the error behavior for set_v and set_i is well-defined by the
documentation: they print nothing on success and an error message on
failure.  The range of valid values is now [0, 20000] for set_v and
[0, 5000] for set_i, matching the voltages and currents that can be
provided by USB Power Delivery.

Bumped version number to 1.0.1, reflecting this bugfix.

docs/console_config.md

 # PD Buddy Sink Serial Console Configuration Interface
 
-Version 1.0.0, 2017-06-05
+Version 1.0.1, 2017-06-19
 
 The PD Buddy Sink can be put into setup mode by holding the Setup button while
 plugging it into a computer.  In this mode, the device does not perform any USB
 
 Usage: `set_v voltage_in_mV`
 
-Sets the voltage of the configuration buffer, in millivolts.
+Sets the voltage of the configuration buffer, in millivolts.  Prints no output
+on success, an error message on failure.
 
 Note: values are rounded down to the nearest Power Delivery voltage unit
 (50 mV).
 
 Usage: `set_i current_in_mA`
 
-Sets the current of the configuration buffer, in milliamperes.
+Sets the current of the configuration buffer, in milliamperes.  Prints no
+output on success, an error message on failure.
 
 Note: values are rounded down to the nearest Power Delivery current unit
 (10 mA).

src/pd.h

 #define PD_PDI_A(pdv) ((pdv) / 100)
 #define PD_PDI_CA(pdv) ((pdv) % 100)
 
+/*
+ * Unit constants
+ */
+#define PD_MV_MIN 0
+#define PD_MV_MAX 20000
+#define PD_PDV_MIN PD_MV2PDV(PD_MV_MIN)
+#define PD_PDV_MAX PD_MV2PDV(PD_MV_MAX)
+#define PD_MA_MIN 0
+#define PD_MA_MAX 5000
+#define PD_PDI_MIN PD_MA2PDI(PD_MA_MIN)
+#define PD_PDI_MAX PD_MA2PDI(PD_MA_MAX)
+
 
 #endif /* PDB_PD_H */

src/shell.c

 
     char *endptr;
     long i = strtol(argv[0], &endptr, 0);
-    if (i >= 0 && i <= UINT16_MAX && endptr > argv[0]) {
+    if (i >= PD_MV_MIN && i <= PD_MV_MAX && endptr > argv[0]) {
         /* Convert mV to the unit used by USB PD */
         tmpcfg.v = PD_MV2PDV(i);
     } else {
 
     char *endptr;
     long i = strtol(argv[0], &endptr, 0);
-    if (i >= 0 && i <= UINT16_MAX && endptr > argv[0]) {
+    if (i >= PD_MA_MIN && i <= PD_MA_MAX && endptr > argv[0]) {
         /* Convert mA to the unit used by USB PD */
         tmpcfg.i = PD_MA2PDI(i);
     } else {

src/usbcfg.c

 static const uint8_t vcom_string3[] = {
     USB_DESC_BYTE(12),                    /* bLength.                         */
     USB_DESC_BYTE(USB_DESCRIPTOR_STRING), /* bDescriptorType.                 */
-    '1', 0, '.', 0, '0', 0, '.', 0, '0', 0
+    '1', 0, '.', 0, '0', 0, '.', 0, '1', 0
 };
 
 /*