Tentative de générateur de signal carré. Je n'arrive pas à dépasser les 40kHz et la résolution après 20kHz est très mauvaise

Genefunc/telnet_srv2.lua

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+-- Serveur telnet pour connexion en remote WIFI, NOUVELLE VERSION !
+-- source: https://github.com/nodemcu/nodemcu-firmware/blob/master/lua_examples/telnet/telnet.lua
+
+print("\n telnet_srv2.lua   zf181215.1326   \n")
+
+local node, table, tmr, wifi, uwrite,     tostring =
+      node, table, tmr, wifi, uart.write, tostring
+
+local function telnet_listener(socket)
+  local insert,       remove,       concat,       heap,      gc   =
+        table.insert, table.remove, table.concat, node.heap, collectgarbage
+  local fifo1, fifo1l, fifo2, fifo2l = {}, 0, {}, 0
+  local s -- s is a copy of the TCP socket if and only if sending is in progress
+  local wdclr, cnt = tmr.wdclr, 0
+  local function debug(fmt, ...)
+    if (...) then fmt = fmt:format(...) end
+    uwrite(0, "\r\nDBG: ",fmt,"\r\n" )
+    cnt = cnt + 1
+    if cnt % 10 then wdclr() end
+  end
+
+  local function flushGarbage()
+    if heap() < 13440 then gc() end
+  end
+
+  local function sendLine()
+     if not s then return end
+
+      if fifo2l + fifo1l == 0 then -- both FIFOs empty, so clear down s
+        s = nil
+        return
+    end
+    flushGarbage()
+    if #fifo2 < 4 then -- Flush FIFO1 into FIFO2
+      insert(fifo2,concat(fifo1))
+      fifo2l, fifo1, fifo1l = fifo2l + fifo1l, {}, 0
+    end
+    local rec =  remove(fifo2,1)        .. (remove(fifo2,1) or '') ..
+                (remove(fifo2,1) or '') .. (remove(fifo2,1) or '')
+    fifo2l = fifo2l - #rec
+    flushGarbage()
+    s:send(rec)
+  end
+
+  local F1_SIZE = 256
+
+  local function queueLine(str)
+    while #str > 0 do  -- this is because str might be longer than the packet size!
+      local k, l = F1_SIZE - fifo1l, #str
+      local chunk
+      if #fifo1 >= 32 or (k < l and k < 16) then
+        insert(fifo2, concat(fifo1))
+        fifo2l, fifo1, fifo1l, k = fifo2l + fifo1l, {}, 0, F1_SIZE
+      end
+      if l > k+16 then -- also tolerate a size overrun of 16 bytes to avoid a split
+        chunk, str = str:sub(1,k), str:sub(k+1)
+      else
+        chunk, str = str, ''
+      end
+      insert(fifo1, chunk)
+      fifo1l = fifo1l + #chunk
+    end
+    if not s and socket then
+      s = socket
+      sendLine()
+    else
+      flushGarbage()
+    end
+  end
+
+  local function receiveLine(s, line)
+    node.input(line)
+  end
+
+  local function disconnect(s)
+    fifo1, fifo1l, fifo2, fifo2l, s = {}, 0, {}, 0, nil
+    node.output(nil)
+  end
+
+  socket:on("receive",       receiveLine)
+  socket:on("disconnection", disconnect)
+  socket:on("sent",          sendLine)
+  node.output(queueLine, 0)
+end
+
+net.createServer(net.TCP, 180):listen(23, telnet_listener)
+print("Telnet server running...\nUsage: telnet -rN ip\n")