Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Atmel/ATSAM3U2E/ADC/CHER#0x0
Channel Enable Register
Channel 0 Enable
Channel 1 Enable
Channel 2 Enable
Channel 3 Enable
Channel 4 Enable
Channel 5 Enable
Channel 6 Enable
Channel 7 Enable
https://github.com/cmsis-svd/cmsis-svd-data