43.8.51 Command register.

Table 43-52. Register Bit Attribute Legend
Symbol	Description	Symbol	Description	Symbol	Description
R	Readable bit	HC	Cleared by Hardware	(Grey cell)	Unimplemented
W	Writable bit	HS	Set by Hardware	X	Bit is unknown at Reset
K	Write to clear	S	Software settable bit	—	—

Name:	PK_Registers__Command
Offset:	0x12004
Reset:	0x0000000F
Property:	RW


Bit	31	30	29	28	27	26	25	24
	CalcR2	FlagB	FlagA	SwapBytes		Edwards	RandProj	RandKE
Access	RW	RW	RW	RW		RW	RW	RW
Reset	0	0	0	0		0	0	0


Bit	23	22	21	20	19	18	17	16
		SelCurve[2:0]			RandMod		OpBytesM1[9:8]
Access		RW	RW	RW	RW		RW	RW
Reset		0	0	0	0		0	0


Bit	15	14	13	12	11	10	9	8
	OpBytesM1[7:0]
Access	RW	RW	RW	RW	RW	RW	RW	RW
Reset	0	0	0	0	0	0	0	0


Bit	7	6	5	4	3	2	1	0
	FieldF	OpeAddr[6:0]
Access	RW	RW	RW	RW	RW	RW	RW	RW
Reset	0	0	0	0	1	1	1	1

Bit 31 – CalcR2 This bit indicates if the IP has to calculate R2 mod N for the next operation. This bit must be set to '1' when a new prime number has been programmed. This bit is used for primitive operations and ignored for the other operations. '0': don't recalculate R2 mod N '1': re-calculate R**2 mod N

Bit 30 – FlagB See operation description.

Bit 29 – FlagA See operation description.

Bit 28 – SwapBytes Swap the bytes on AHB interface: '0': Native format (little endian) '1': Byte swapped (big endian) See also section 4.2.1. This bit must be programmed before writing/reading any data in data memory.

Bit 26 – Edwards Enable Edwards curve (see operation description).

Bit 25 – RandProj Enable randomization of projective coordinates (counter-measure).

Bit 24 – RandKE Enable randomization of exponent/scalar (counter-measure).

Bits 22:20 – SelCurve[2:0] Enable accelerator for specific curve modulus: 0x0: No acceleration (default) 0x1: P256 0x2: P384 0x3: P521 0x4: P192 0x5: Curve25519 0x6: Ed25519 This field has no effect when the optional acceleration hardware is not included.

Bit 19 – RandMod Enable randomization of modulus (counter-measure).

Bits 17:8 – OpBytesM1[9:0] This field defines the size (= number of bytes minus one) of the operands for the current operation. Possible values are limited by the maximum supported operand size. Examples: - 0x014 -> ECC on curve K-163 - 0x01F -> ECC on curve P-256 - 0x02F -> ECC on curve P-384 - 0x033 -> ECC on curve K-409 - 0x041 -> ECC on curve P-521 - 0x07F -> 1024-bit RSA - 0x09F -> 1280-bit RSA - 0x1FF -> 4096-bit RSA - 0x3FF -> 8192-bit RSA

Bit 7 – FieldF '0': Field is GF(p) '1': Field is GF(2**m)

Bits 6:0 – OpeAddr[6:0] This field defines the operation to be performed. See documentation for more details.

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