A bit is a 0 or 1.
A byte is 8 bits, 00000000.
Decimal is a base-10 number system, with digits 0,1,2,3,4,5,6,7,8,9, forming numbers like 34. A two digit decimal number existing in the range 0 -> 99, which is 100 (10^2) possible numbers.
Hex, short for Hexadecimal, is a base-16 number system, with digits 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F, forming numbers like 0x34, 0xC4. They can also be written with a trailing h like 5Ch. Since each digit represents 16 numbers, there are 256 (16^2) numbers in the range 0x0 -> 0xFF. Some useful hex numbers to recognise are:
| Hex | Binary |
|---|---|
| 3 | 11 |
| 7 | 111 |
| 8 | 1000 |
| F | 1111 |
| 10 | 10000 |
| 1F | 11111 |
| FF | 11111111 |
'Word' size is a property of a computer architecture and denotes the number of bits that a CPU can process at one time. The word size also usually corresponds to the address size of the computer. '32-bit' computers have a word size of 32 and usually use 32-bit memory addresses. Normally these computers are 'byte-addressable', meaning each of the 2^32 memory addresses point to one byte (8 bits, 2 hex digits) of memory.
The LED display is acces via the GPIO pins.
- P0 GPIO_BASE = 0x50000000
- P1 GPIO_BASE = 0x50000300
- P0 covers P0.00 to P0.31
- P0.15 = row3
- P0.31 = col3
"A UART transmission sequence is started by triggering the STARTTX task.
Bytes are transmitted by writing to the TXD register. When a byte has been successfully transmitted, the UART will generate a TXDRDY event after which a new byte can be written to the TXD register. A UART transmission sequence is stopped immediately by triggering the STOPTX task." from https://docs.nordicsemi.com/bundle/ps_nrf52833/page/uart.html
- P0.06 = UART_INT_RX
- P1.08 = UART_INT_TX