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Clicker 4 - Access Method 5:
Scanning the grid using a single switch to select

Using scanning with a single switch to select

You can use a single switch with Clicker as it supports scanning of the cells within each grid. Do not confuse this with Access Method 2 (using a single switch as a left-click) as that's a different kettle of fish altogether!

The idea of single-switch scanning is that the user is presented with a list of options that the computer cycles through. When it reaches the option they're after, the user hits the switch and the computer selects it. This allows people with very little physical control to have full access to grids.

Single switch scanning can be rather slow and is very frustrating for the user if they miss a cell and have to wait for the scanning box to go all the way round the grid again. Getting the timing right can also be quite demanding and requires good anticipation skills. Your pupil needs to stay focused with the computer at all times and concentrate on the moving scanning box.

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Setting it up

In order to use single-switch scanning you will need to procure a suitable switch and a method of getting the switch into the computer.

Once you've got your switch successfully connected to your compute you'll need to tell Clicker that it's there. Here's how:

User Access menu item

Make sure Clicker is running and that you are logged on as the person you want these settings to affect.

Now got to the Options menu and click on User Access.

Clicker 4 User Access Options

This should bring up the Access dialog box. Under Access Method select Single Switch.

Selecting your switch COM port

Now you will have to tell Clicker where the switch is plugged in. Go to the Switch Connection tab and choose from the list whichever is relevant to you.

If you're using the Crick USB Switch Interface box then select this option from the list.

If you are using a serial port adapter for your switches then you'll need to select one of the COM ports. If you're unsure then start at COM 1, click OK, and try your switch. If you can't select a cell try plugging your switch into another jack port. If things still don't go anywhere then go back to Options, User Access, Switch Connection and try COM 2.

If you're using switches that plug into your keyboard then select the Up & Left Arrow Keys option. If you can't set your switches to these keys then you'll have to load the third-party switch driver that was supplied with your switch-enabled keyboard or other interface.

Adjusting the Switch Timings

Once you've got Clicker scanning and your switch selecting, you'll need to adjust the timings so that it's not to slow or fast for your user. Go to Options and User Access again. This time click the Timings tab.

The first setting is the Scan Delay. This specifies the amount of time that the grid will wait at a cell before it moves on to the next one. Too slow a setting and it could take ages to scan a grid. Too fast and your user might not be able to respond in time and hit the switch before it's moved on to the next cell.

A setting of 20 is around one second on my computer, but it could vary.

If your user tends to tap the switch at the wrong times, then you could try putting up the Acceptance Delay. This will mean that your user will have to hold the switch down for a certain amount of time before clicker will accept and select the cell.

A setting of 20 forces the user to hold the switch down for around half a second.

The Debounce Delay is important as some switch users tend to tremble when they hit their switch. By raising the debounce value you'll be able to stop this from happening. Clicker will accept the first switch, but will then wait for the specified time before it will accept any more. Raising it too high could stop your user from being able to select proceeding cells, so watch out!

Now go back to Clicker Access Methods Contents or move forward to Method 6: Using two switches