Right now the answer is no... If your run carthage help update you'll see
Update and rebuild the project's dependencies
[--configuration Release]
the Xcode configuration to build (ignored if --no-build option is present)
[--platform all]
the platform to build for (ignored if --no-build option is present)
[--verbose]
print xcodebuild output inline (ignored if --no-build option is present)
[--no-build]
skip the building of dependencies after updating
[--use-ssh]
use SSH for downloading GitHub repositories
[--use-submodules]
add dependencies as Git submodules
[--no-use-binaries]
check out dependency repositories even when prebuilt frameworks exist (ignored if --no-build option is present)
[--color auto]
whether to apply color and terminal formatting (one of ‘auto’, ‘always’, or ‘never’)
[/path/to/your/app]
the directory containing the Carthage project
As you can see there is no mention to an option to specify only one dependency to update.
carthage [update|bootstrap|checkout|build] [dependency1] [dependency2] [--no-use-binaries] [--platform <name>]
//--no-use-binaries - does not use prebuild binary and use source code
//--platform - specify a platform
The longest phase is a carthage build(xcodebuild) step because:
carthage build generates fat binary which is built using lipo[About]
Carthage builds all shared frameworks schemes of a project. If you know which exactly schema which you need you can:
[UI] Open built project from Carthage/Checkouts folder -> Manage Schemes... -> check specific schemes
[Manually] Leave specific schemes at xcschemes folder .../Carthage/Checkouts/<dependency>/<project>.xcodeproj/xcshareddata/xcschemes/<schema>.xcscheme
Looks like carthage update repo-name doesn't work on Carthage 0.36.0.
I solved this problem by manually updating Carthage.resolved. For example, add to a Cartfile a new dependency: