As a next step i could see STM32 or (people might disagree with me on this) nRF. You could also first branch into low-level driver development in C on your existing boards. The STM-Part: -The basic b*tch Arm Cortex-M architecture is widely used Everything from small&low-cost to multicore and wireless +Inexpensive and available Development-boards +Free IDE, inexpensive, sometimes included Debugger +Big (in no way perfect, but extensive) Driver support +nicely documented and active support forum -not so nice for wireless (except ofc with external modules) -kind of expensive in low quantities in ic-form You could start in the STM-cubeIDE and when you get comfortable you could lear about the Build-process (gcc, make and similar) and make the switch to CubeMX + Vscode/eclipse/sublime (whatever you prefer, i like VSCode). Learning about these processes somewhat makes you plattform independent and that is imo a valuable step. The nRF-Part: -Wireless Also Arm cortex-M +Great for BLE, Zigbee, theead +Widely used in consumer orientated industry Programming far away from the underlying hardware (Zephyr RTOS) +nicely documented and active support forum +also extensive driver support +also small and inexpensive Dev-boards (dongle - 10bucks) -debugger is supposed to be generic SWD, i have not managed to get it to work with anything except jlink... Has a bootloader tho and some dev-board include an ebedded J-link -less variety then STM Basically: this if you want to go into Wireless stuff The low-level driver C: (i assume you ment that by "assembly") There is quite a big Chance you will need to get into direct-register-access or Datasheet-near programming sooner or later when continuing on this "path of Leveling-Up". Might aswell get it over with on an Architecture you are familiar with. No one (that i know) writes in assembly (Except for startup-code), you can do direct bit and register manipulations in C, no problem. You could for example write a driver for the I2C controller or an external i2c device. This has no real advantage to using existing ones, but for an exercise/learning its great. Sorry for spelling in advance (non native), and keep in mind: to you this is just an opinion of a random dude on the internet, this might not be your optimal way and you do what you want Edit:spacings, +1Pt to nRF More on reddit.com

i had arduino to programme the board before but the programme not loading up to read the board now any help plz More on forum.arduino.cc

You flash them much the same way you'd flash any arduino, there's plenty arduino tutorials around. IIRC teensy comes with a bootloader, which makes things simpler (you don't need a dedicated programmer), the QMK documentation has ample info on how to do that. Speaking of QMK, it's the firmware you probably want to use, the popular teensy variant for QMK is 2.0, others have other processors which changes how you flash them (to some extend). Anything that says "Teensy 2.0 compatible" (they like to use that term) should do the job. More on reddit.com

Both involve using Arduino.h .

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