diff options
Diffstat (limited to 'glucometerutils/support/hiddevice.py')
| -rw-r--r-- | glucometerutils/support/hiddevice.py | 58 |
1 files changed, 25 insertions, 33 deletions
diff --git a/glucometerutils/support/hiddevice.py b/glucometerutils/support/hiddevice.py index 43461e7..41ad17c 100644 --- a/glucometerutils/support/hiddevice.py +++ b/glucometerutils/support/hiddevice.py @@ -6,44 +6,34 @@ import logging import os -from typing import BinaryIO, Optional, Text +from typing import BinaryIO, Optional, Text, Tuple from glucometerutils import exceptions -class HidDevice: - """A device speaking USB HID protocol driver base. +class HidSession: + """An access class to speak to USB HID based devices. - This class does not implement an actual driver by itself, but provides an - easier access to the boilerplate code required for speaking USB HID. - - This helper wraps around an optional dependency on hidapi library: if - present the driver will auto-detect the device, if not the device path needs - to be provided and should point to a device implementing Linux's hidraw - interface. - - The following constants can be set by the actual drivers: - - USB_VENDOR_ID: (int) USB vendor ID for the device. - USB_PRODUCT_ID: (int) USB product ID for the device. - - If the VID/PID pair is not provided, the driver will require a device path - to be used. - - Optional parameters available: - - TIMEOUT_MS: (int, default: 0) the read timeout in milliseconds, used - for hidapi reads only. If < 1, hidapi will be provided no timeout. + This class does not implement a full driver, but rather provide simpler read/write + methods abstracting the HID library. """ - USB_VENDOR_ID = None # type: int - USB_PRODUCT_ID = None # type: int + def __init__(self, usb_id, device, timeout_ms=0): + # type: (Optional[Tuple[int, int]], Optional[Text], int) -> None + """Construct a new session object. + + Args: + usb_id: Optional pair of vendor_id and product_id for the session. + This is required to use the hidapi library. + device: Optional path to Linux hidraw-style device path. If not provided, + usb_id needs to be provided instead. + timeout_ms: Timeout in milliseconds for read operations. Only relevant when + using hidapi library. + """ - TIMEOUT_MS = 0 # type: int + self._timeout_ms = timeout_ms - def __init__(self, device): - # type: (Optional[Text]) -> None - if None in (self.USB_VENDOR_ID, self.USB_PRODUCT_ID) and not device: + if not usb_id and not device: raise exceptions.CommandLineError( "--device parameter is required, should point to a /dev/hidraw " "device node representing the meter." @@ -63,8 +53,10 @@ class HidDevice: try: import hid + assert usb_id + vendor_id, product_id = usb_id self.hidapi_handle_ = hid.device() - self.hidapi_handle_.open(self.USB_VENDOR_ID, self.USB_PRODUCT_ID) + self.hidapi_handle_.open(vendor_id, product_id) except ImportError: raise exceptions.ConnectionFailed( message='Missing requied "hidapi" module.' @@ -74,7 +66,7 @@ class HidDevice: message=f"Unable to connect to meter: {e}." ) - def _write(self, report): + def write(self, report): # type: (bytes) -> None """Writes a report to the HID handle.""" @@ -86,7 +78,7 @@ class HidDevice: if written < 0: raise exceptions.CommandError() - def _read(self, size=64): + def read(self, size=64): # type: (int) -> bytes """Read a report from the HID handle. @@ -96,4 +88,4 @@ class HidDevice: if self.handle_: return bytes(self.handle_.read(size)) - return bytes(self.hidapi_handle_.read(size, timeout_ms=self.TIMEOUT_MS)) + return bytes(self.hidapi_handle_.read(size, timeout_ms=self._timeout_ms)) |