Electronic – What does apostrophe mean for a register description in a datasheet e.g. 4’d5


The datasheet lists something like this:

[0x01f] EPRXREG

    EPRXLock[3:0] = 4'd5;
    EPRXReLock[3:0] = 4'd5

I understand that it is an 8-bit register at address 0x01f, it contains 2 fields and each of them is 4 bits wide ([3:0] and the 4 in 4'd5). But what is 'd5?

Other registers have

4'd12  1'b0  4'h4  4'hF  7'd32

Best Answer

4'd5 indicates a four-bit value, expressed in decimal as 5. It's the same as 4'b101 (1012 = 510).

Likewise, 4'hF is a four-bit value indicating 0xF in hex; octal may also be seen (e.g. 4'hF can also be denoted as 4'o17)

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