python 操作FT232H——（1）准备工作与IO输出方波信号_ft232h编程

1.准备工作：

python环境：

安装python 环境，我目前使用的是pycharm2023.2.1 community Edition 版本

需要注意设置python解释器的版本及关联本地库，这样就不需要在新的工程中安装库文件了，（当然也有缺点，在另外新的开发环境下，需要重安装一次）

在设置中找到python 解释器，虚拟环境使用本地。

FTDI库：

我选择的是FTD2xx，安装命名为 ：pip install ftds2xx;

Device driver

As standard, when an FTDI device is plugged into a Windows PC, the operating system loads the default Virtual Com Port driver, that can only handle asynchronous serial (RS232-type) protocols. However, we want to be a bit more adventurous, so need to substitute the ‘d2xx’ driver, available from the FTDI drivers page. A quick way to check which driver is active is to look at the Device Manager; if the FTDI part appears as a COM port, it is asynchronous-only.

Use ‘pip’ to install a Python library that will access the d2xx driver; there are several available (such as pyftdi, pylibftdi) but the only one that worked seamlessly with Python 2.7 and 3.x on my systems was the simplest: ftd2xx, which is just a CTYPES wrapper round the d2xx API

2.代码及操作--连接FTDI设备，并读设备信息

import sys, ftd2xx as ftd
d = ftd.open(0)    # Open first FTDI device
print(d.getDeviceInfo())
print(hex(d.getDriverVersion()))
print(hex(d.getComPortNumber()))

执行结果为： 

{'type': 8, 'id': 67330068, 'description': b'Single RS232-HS', 'serial': b''}

注意要连接上设备，否则会报错误：

Traceback (most recent call last):
  File "F:\python_t\test_proj\main.py", line 37, in <module>
    d = ftd.open(0)
        ^^^^^^^^^^^
  File "F:\python_t\test_proj\venv\Lib\site-packages\ftd2xx\ftd2xx.py", line 268, in open
    call_ft(_ft.FT_Open, dev, c.byref(h))
  File "F:\python_t\test_proj\venv\Lib\site-packages\ftd2xx\ftd2xx.py", line 178, in call_ft
    raise DeviceError(status)
ftd2xx.ftd2xx.DeviceError: DEVICE_NOT_FOUND

另外的设备打开方式：

    def testopenEx(self):
        dev0 = None
        try:
            devices = ftd2xx.listDevices()
            if devices is None:
                raise DeviceError("Device not found")
            dev0_id = devices[0]
            dev0 = ftd2xx.openEx(dev0_id)
            self.assertIsInstance(dev0, ftd2xx.FTD2XX)
            self.assertEqual(dev0.getDeviceInfo()["serial"], dev0_id)
        except AssertionError:
            raise
        finally:
            if dev0:
                dev0.close()

 3.代码操作-DO 输出3个方波信号：

（Bitbang mode: toggling an I/O pin）

import sys, ftd2xx as ftd
 
print("hello")
d = ftd.open(0)
print(d.getDeviceInfo())
print(hex(d.getDriverVersion()))
print(hex(d.getComPortNumber()))
 
OP = 0x01            # Bit mask for output D0
d.setBitMode(OP, 1)  # Set pin as output, and async bitbang mode
d.write(str(OP))     # Set output high
d.write(str(0))      # Set output low
d.write(str(OP))     # Set output high
d.write(str(0))      # Set output low
d.write(str(OP))     # Set output high
d.write(str(0))      # Set output low