diff --git a/docs/lua-modules/liquidcrystal.md b/docs/lua-modules/liquidcrystal.md index bf647822..1f8d1b6b 100644 --- a/docs/lua-modules/liquidcrystal.md +++ b/docs/lua-modules/liquidcrystal.md @@ -237,6 +237,12 @@ liquidcrystal:blink(true) ## liquidcrystal.busy Get busy status of the LCD. When using GPIO backend without `rw` argument specification function does nothing. +!!! note + At least some HD44780s and/or interfaces have been observed to count polling + the busy flag as grounds for incrementing their position in memory. This is + mysterious, but software should restore the position after observing that the + busy flag is clear. + #### Syntax `liquidcrystal.busy(self)` @@ -429,6 +435,11 @@ liquidcrystal:leftToRight() ## liquidcrystal.position Get current position of the cursor. Position is 0 indexed. When using GPIO backend without `rw` argument specification function does nothing. +!!! note + At least some HD44780s and/or interfaces have been observed to count reading + the position as grounds for incrementing their position in memory. This is + mysterious, but software likely intends to restore the position anyway. + #### Syntax `liquidcrystal.position(self)` diff --git a/lua_modules/liquidcrystal/lc-i2c4bit.lua b/lua_modules/liquidcrystal/lc-i2c4bit.lua index dc4011b6..0d286a02 100644 --- a/lua_modules/liquidcrystal/lc-i2c4bit.lua +++ b/lua_modules/liquidcrystal/lc-i2c4bit.lua @@ -22,27 +22,27 @@ return function(bus_args) -- The onus is on us to maintain the backlight state local backlight = true - local function send4bitI2C(value, rs_en, rw_en, read) - local function exchange(data, unset_read) - local rv = data + local function exchange(data, read) + local rv = data + i2c.start(busid) + i2c.address(busid, busad, i2c.TRANSMITTER) + i2c.write(busid, bit.set(data, en)) -- set data with en + if read then + i2c.start(busid) -- read 1 byte and go back to tx mode + i2c.address(busid, busad, i2c.RECEIVER) + rv = i2c.read(busid, 1):byte(1) i2c.start(busid) i2c.address(busid, busad, i2c.TRANSMITTER) - i2c.write(busid, bit.set(data, en)) - if read then - i2c.start(busid) - i2c.address(busid, busad, i2c.RECEIVER) - rv = i2c.read(busid, 1):byte(1) - i2c.start(busid) - i2c.address(busid, busad, i2c.TRANSMITTER) - if unset_read then data = bit.bor(bit.bit(rs), - bit.bit(rw), - backlight and bit.bit(bl) or 0) end - i2c.write(busid, bit.set(data, en)) - end - i2c.write(busid, bit.clear(data, en)) - i2c.stop(busid) - return rv end + i2c.write(busid, data) -- lower en + i2c.stop(busid) + return rv + end + + local function send4bitI2C(value, rs_en, rw_en) + local meta = bit.bor(rs_en and bit.bit(rs) or 0, + rw_en and bit.bit(rw) or 0, + backlight and bit.bit(bl) or 0) local lo = bit.bor(bit.isset(value, 0) and bit.bit(d4) or 0, bit.isset(value, 1) and bit.bit(d5) or 0, bit.isset(value, 2) and bit.bit(d6) or 0, @@ -51,11 +51,8 @@ return function(bus_args) bit.isset(value, 5) and bit.bit(d5) or 0, bit.isset(value, 6) and bit.bit(d6) or 0, bit.isset(value, 7) and bit.bit(d7) or 0) - local cmd = bit.bor(rs_en and bit.bit(rs) or 0, - rw_en and bit.bit(rw) or 0, - backlight and bit.bit(bl) or 0) - hi = exchange(bit.bor(cmd, hi), false) - lo = exchange(bit.bor(cmd, lo), true) + hi = exchange(bit.bor(meta, hi), rw_en) + lo = exchange(bit.bor(meta, lo), rw_en) return bit.bor(bit.lshift(bit.isset(lo, d4) and 1 or 0, 0), bit.lshift(bit.isset(lo, d5) and 1 or 0, 1), bit.lshift(bit.isset(lo, d6) and 1 or 0, 2), @@ -66,36 +63,45 @@ return function(bus_args) bit.lshift(bit.isset(hi, d7) and 1 or 0, 7)) end - -- init sequence from datasheet - send4bitI2C(0x33, false, false, false) - send4bitI2C(0x32, false, false, false) + -- init sequence from datasheet (Figure 24) + local function justsend(what) + i2c.start(busid) + i2c.address(busid, busad, i2c.TRANSMITTER) + i2c.write(busid, bit.set(what, en)) + i2c.write(busid, what) + i2c.stop(busid) + end + local three = bit.bor(bit.bit(d4), bit.bit(d5)) + justsend(three) + tmr.delay(5) + justsend(three) + tmr.delay(1) + justsend(three) + tmr.delay(1) + justsend(bit.bit(d5)) + -- we are now primed for the FUNCTIONSET command from the liquidcrystal ctor -- Return backend object return { fourbits = true, command = function (_, cmd) - return send4bitI2C(cmd, false, false, false) + return send4bitI2C(cmd, false, false) end, busy = function(_) - local rv = send4bitI2C(0xff, false, true, true) - send4bitI2C(bit.bor(0x80, bit.clear(rv, 7)), false, false, false) - return bit.isset(rv, 7) + return bit.isset(send4bitI2C(0xff, false, true), 7) end, position = function(_) - local rv = bit.clear(send4bitI2C(0xff, false, true, true), 7) - send4bitI2C(bit.bor(0x80, rv), false, false, false) - return rv + return bit.clear(send4bitI2C(0xff, false, true), 7) end, write = function(_, value) - return send4bitI2C(value, true, false, false) + return send4bitI2C(value, true, false) end, read = function(_) - return send4bitI2C(0xff, true, true, true) + return send4bitI2C(0xff, true, true) end, backlight = function(_, on) backlight = on - local rv = bit.clear(send4bitI2C(0xff, false, true, true), 7) - send4bitI2C(bit.bor(0x80, rv), false, false, false) + send4bitI2C(0, false, false) -- No-op return on end, } diff --git a/tests/NTest_lcd_i2c4bit.lua b/tests/NTest_lcd_i2c4bit.lua new file mode 100644 index 00000000..e9aa543d --- /dev/null +++ b/tests/NTest_lcd_i2c4bit.lua @@ -0,0 +1,83 @@ +-- Run LiquidCrystal through some basic tests. Requires `liquidcrystal.lua` +-- and `l2-i2c4bit.lua` available available to `require`. +-- +-- This file ought to be named "NTest_liquidcrystal_i2c4bit" or something, +-- but it has its current name due to our default SPIFFS filename length limit. + +local N = ... +N = (N or require "NTest")("liquidcrystal-i2c4bit") + +local metalcd +local metaback +local backend +local lcd + +collectgarbage() +print("HEAP init", node.heap()) + +metalcd = require "liquidcrystal" +collectgarbage() print("HEAP constructor imported ", node.heap()) + +metaback = require "lc-i2c4bit" +collectgarbage() print("HEAP backend imported ", node.heap()) + +backend = metaback({ + address = 0x27, + id = 0, + speed = i2c.SLOW, + sda = 2, + scl = 1, +}) +collectgarbage() print("HEAP backend built", node.heap()) + +lcd = metalcd(backend, false, true, 20) +collectgarbage() print("HEAP lcd built", node.heap()) + +print("waiting for LCD to be unbusy before testing...") +while lcd:busy() do end + +N.test("custom character", function() + local glyph = { 0x1F, 0x15, 0x1B, 0x15, 0x1F, 0x10, 0x10, 0x0 } + lcd:customChar(0, glyph) + ok(eq(glyph,lcd:readCustom(0)), "read back") +end) + +N.test("draw and readback", function() + lcd:cursorMove(0) + lcd:write("abc") + lcd:cursorMove(10,1) + lcd:write("de") + lcd:cursorMove(10,2) + lcd:write("fg") + lcd:cursorMove(12,3) + lcd:write("hi\000") + lcd:cursorMove(18,4) + lcd:write("jk") + + lcd:home() ok(eq(0x61, lcd:read()), "read back 'a'") + ok(eq(0x62, lcd:read()), "read back 'b'") + lcd:cursorMove(11,1) ok(eq(0x65, lcd:read()), "read back 'e'") + lcd:cursorMove(11,2) ok(eq(0x67, lcd:read()), "read back 'g'") + lcd:cursorMove(13,3) ok(eq(0x69, lcd:read()), "read back 'i'") + lcd:cursorMove(14,3) ok(eq(0x00, lcd:read()), "read back 0" ) + lcd:cursorMove(19,4) ok(eq(0x6B, lcd:read()), "read back 'k'") + +end) + +N.test("update home", function() + lcd:home() lcd:write("l") + lcd:home() ok(eq(0x6C, lcd:read())) +end) + +N.testasync("clear", function(next) + -- clear and poll busy + lcd:clear() + tmr.create():alarm(5, tmr.ALARM_SEMI, function(tp) + if lcd:busy() then tp:start() else next() end + end) + lcd:home() -- work around busy polling incrementing position (XXX) + ok(eq(0x20, lcd:read()), "is space") + ok(eq(1, lcd:position())) -- having just read 1 from home, we should be at 1 +end) + +