Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Data Sheet
Product codes
ATSAMD21-XPRO
766
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181C–SAM-D21_Datasheet–07/2014
31.8.1.6 Pad Calibration
Name:
PADCAL
Offset:
0x28
Reset:
0x0000
Property:
Write-Protected
The Pad Calibration values must be loaded from the NVM Software Calibration Area into the USB Pad Calibration
register by software, before enabling the USB, to achieve the specified accuracy. Refer to
register by software, before enabling the USB, to achieve the specified accuracy. Refer to
for further details.
z
Bit 15 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 14:12 – TRIM: Trim bits for DP/DM
These bits calibrate the matching of rise/fall of DP/DM.
These bits calibrate the matching of rise/fall of DP/DM.
z
Bit 11 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 10:6 – TRANSN: Trimmable Output Driver Impedance N
These bits calibrate the NMOS output impedance of DP/DM drivers.
These bits calibrate the NMOS output impedance of DP/DM drivers.
z
Bit 5 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
This bit is unused and reserved for future use. For compatibility with future devices, always write this bit to zero
when this register is written. This bit will always return zero when read.
z
Bits 4:0 – TRANSP: Trimmable Output Driver Impedance P
These bits calibrate the PMOS output impedance of DP/DM drivers.
These bits calibrate the PMOS output impedance of DP/DM drivers.
Bit
15
14
13
12
11
10
9
8
TRIM[2:0]
TRANSN[4:2]
Access
R
R/W
R/W
R/W
R
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
TRANSN[1:0]
TRANSP[4:0]
Access
R/W
R/W
R
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0