Split pea soup won't soften. Any way to soften the peas without burning?
Starting with more water than you think you need, keeping the lid on for a bit and then stirring a lot while it reduces to the desired consistency should be all you need to do. Don't go far from it once it starts to thicken because it will need too much stirring. 

You can cook split peas in a slow cooker, but I haven't found the softening very reliable. A fast boil before you start might help.