example for writing file in looping luarpc

autorun.lua

stm32.enc.init(3)
stm32.enc.setidxtrig(cpu.INT_GPIO_POSEDGE, pio.PB_5, 3, 32768)

local state = {}
local stime

cycletime = 20000
tdiff = 0

function control()
end

iter = 1

handle = rpc.listen(0,0)
stime = tmr.start(tmr.SYS_TIMER)
while true do
   -- Check for pending RPC request
   if rpc.peek( handle ) then
      rpc.dispatch( handle )
   end
   control()
   tdiff = tmr.gettimediff( tmr.SYS_TIMER, stime, tmr.read(tmr.SYS_TIMER) )
   tmr.delay( 1, cycletime - (tmr.read(tmr.SYS_TIMER) % cycletime ) )
   stime = tmr.read(tmr.SYS_TIMER)
   iter = iter+1
end

file_write_control.lua

function error_handler (message)
	io.write ("MY ERROR: " .. message .. "\n");
end

rpc.on_error (error_handler);

slave,err = rpc.connect ("/dev/tty.usbserial-FTDXSDBS");

state_init = {fd = nil, fname='/mmc/testfile4.txt', iter = 1}

function control_open_write()
	if state.fd == nil then
		state.fd = io.open(state.fname, "w+")
	else
		state.fd:write(string.format("%d, %d\n", state.iter, tdiff))
		state.fd:flush()
	end
	state.iter = state.iter+1
end

function control_close()
	if state.fd ~= nil then
		state.fd:flush()
		state.fd:close()
		state.fd = nil
	end
end

slave.state = state_init

slave.control = control_open_write

-- wait for some time to pass, then close with

slave.control = control_close