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everyone welcome to controllers tech
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i have already covered a video on usb
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where i interfaced the usb flash drive
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well this is another video on usb host
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and today i will show you
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how to interface hid with sdm32
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i will interface both the mouse and the
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let's start by creating a project in
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first i am using stm32 discovery board
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give some name to the project and click
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let's clear the default pin outs
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first of all i am selecting the external
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crystal for the clock
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now go to usb otg fs and enable the host
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also enable the v bus so that we can
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provide power to the usb device
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go to usb host and enable the hid class
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if you notice here there is no solution
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bus this is because we haven't enabled
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open the user manual for your board
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as you can see here the supply for the v
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bus can be enabled by the pin
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pc 0. it is connected to enable pin
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which is active low pin so to turn on
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we need to pull the pin pc 0 to low
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and then this 3 volt supply will be
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select the pin pc 0 as output
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as you can see now there is a solution
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bus let's enable the uart
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so that we can see the output on the
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now the clock setup i have eight
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megahertz external crystal
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and i want the system to run at maximum
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this is it for the setup click save to
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here is our main file
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first of all let's include the usb h id
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file we will be using the functions from
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here we are interested in hid event
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this will be called whenever we receive
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this is a common function for both the
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mouse and the keyboard
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so we need to check if the data is
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received from the mouse
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or from the keyboard hid get device type
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will be used for this purpose
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if the data is received from the mouse
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we will perform the operations here
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and we will write a similar function for
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first define a pointer to the mouse info
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basically this structure will contains
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all the data from the mouse
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that we will receive the data contains
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the movement in x-axis
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in y-axis and the indication of which
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button is pressed on the mouse
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here we will receive and store the data
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the movement in the x and the y axis
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and that's why it is hard to understand
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to make it look simpler i am making some
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this way the movement in one direction
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while in the other direction it will be
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now we will store all these values in a
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and finally send them to you art
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we will do the same steps for the
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first define the keyboard type def
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then get the keyboard data and store it
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in keyboard we have a function to get
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the ascii code of the key
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we will get the ascii code from the
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structure where we stored the data
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and store it in a variable
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now store all these values in a buffer
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and finally send them to you
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let's build this code now
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some error in the variables here
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let me just quickly fix that
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also let's add the stdio.h
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for the s printf to work
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now everything is good let's flash this
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i am connecting the mouse via the otg
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open the serial monitor to view the data
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move the mouse to the left as you can
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see the x values are negative
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you can observe how the values are
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they decreased from 0 to minus 4 minus
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minus 22 minus 30 basically the faster
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the higher this value will be
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and as the mouse slows down the values
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started increasing and finally become
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when the mouse stops this is the
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movement in the right direction
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the x values are positive now
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they follow the same pattern as they did
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in the left direction
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now as i am moving the mouse up the y
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value is changing in the negative
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the mouse is moving down this time
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y values are positive and almost no
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now let's test the buttons this is the
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you can see the button one value was one
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when i press the button
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and becomes zero when i release it for
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button 2 value becomes 1 when i press
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and becomes 0 when i release it
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and for the middle click the button 3
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let's see one more time
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left click right click
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middle click this is it for the mouse
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now let's remove the mouse and connect
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we will keep our program running as we
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have included both the mouse and
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keyboard in our callback function
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so when we press the key the character
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and when we release the key a null gets
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we can print the capital characters
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during testing i found that the
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bluetooth mouse and keyboards don't work
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so try using the wired ones
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i hope you guys understood this video
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i will try to make use of this in my
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where i will try to display the movement
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and the keyboard characters on the tft
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this is it for this video you can
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download the code from the link in the
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leave comments if you have any doubts
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keep watching and have a nice day
