Newbie: how to talk to USB serial device from my app?

Question

Hi,

I am starting to look at communicating with a USB interface which I understand behaves like a serial device. I am now looking at documentation and sample code to help me do that. I found some documentation, but it's all in the "archive" section of the developer documentation, which to me looks like it's more or less out of date.

Did I miss something? What would be some suggestions to start learning about doing that?

FWIW, I would like to communicate with some marine NMEA USB interfaces. NMEA 0183 but NMEA 2000 too. The ones I have are made by Digital Yacht and Yacht Devices.

Thanks

JD

macOS

317

Posted by

jdmuys

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Answer 1

Could you show the code you tried so far ?

If that can help, here is an example to retrieve information of an USB disk.

Code Block import Foundation
func findRemovableVolumes() -> [URL] {
    
    var allMountedURL = [URL]()
    let keys: [URLResourceKey] = [.volumeNameKey, .volumeIsRemovableKey, .volumeIsEjectableKey]
    let paths = FileManager().mountedVolumeURLs(includingResourceValuesForKeys: keys, options: [])
    if let urls = paths {
        for url in urls {
            let components = url.pathComponents
            if components.count > 1 && components[1] == "Volumes" {
                allMountedURL.append(url)
            }
        }
    }
    return allMountedURL
}
func buildFileURL(driveUrl: URL) -> URL {
    
    let fileName = "My file"
    let fileURL = driveUrl.appendingPathComponent(fileName).appendingPathExtension("txt")
    
    return fileURL
}
func getSerialAndSize(_ url: URL) -> (String, Int, Bool) {
    
    var officialVendor = false
    
    if let session = DASessionCreate(nil) {
        if let disk : DADisk = DADiskCreateFromVolumePath(nil, session, url as CFURL) {
            // We found a mount point...
            let ioService : io_service_t = DADiskCopyIOMedia(disk)
            let key = "USB Serial Number"
            
            let options : IOOptionBits = IOOptionBits(kIORegistryIterateParents) |
                IOOptionBits(kIORegistryIterateRecursively)
            
            if let sSerial : CFTypeRef = IORegistryEntrySearchCFProperty(ioService, kIOServicePlane, key as CFString, nil, options) {
                
                let dico: CFDictionary = DADiskCopyDescription(disk)!
                 let vendor = (dico as NSDictionary)["DADeviceVendor"] as? String ?? "--"
                officialVendor = vendor == "VendorCo" 
                let driveCapacity = (dico as NSDictionary)["DAMediaSize"] as? Int ?? 0
                return (String(describing: sSerial), driveCapacity, officialVendor)
            } else {    
                return ("", 0, false)  
            }
        }
        
    }
    
    return ("", 0, false)
    
}

Posted by

Claude31

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Newbie: how to talk to USB serial device from my app?

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