Creating a simple step sequencer that sends notes and keyboard letters

Hi,
I am looking for semeone who can help me create a step sequencer.

Here is a description of the initial project,
I am adding some functionalities so it will evolve a llittle from this but basically
it will have 9 pads 1 switch for selecting items and 16 pads for note/key selection on the sequencer pad
1 usb output

the sequencer will be of a size a little bit smaller then a computer keyboard
with a row of trigger pads like on the tr808 drum machine, 16 pads,
above these pads will be a row of 8 buttons to assign sounds.
A tempo adjustment knob a usb out plug one led to show tempo

The sequencer might have midi implemented but the first and main system
is with computer keyboard keys, with numbers, so basically i would like to be able
to choose a number like 1, assign it to steps the 16 pads, then choose the number 2 and assign also, etc…
so it will be sending through a usb cable a rythm pattern with numbers (following a choosen tempo)
like: 1…2…1…2…,
so I can send this pattern to different apps like an online synthesizer.
Numbers can be choosed and all the letters on the keyboard as well.




So as you can see it is not a very complicated project but it does involve some knowledge
with programming.
I would like to see your previous projects and
get this project on the road.
thank you