tests/drivers: add dedicated hd44780_i2c test

drivers/include/hd44780.h

@@ -13,7 +13,8 @@
  * @ingroup     drivers_display
  * @brief       Driver for the Hitachi HD44780 LCD driver
  *
- * @note        The driver currently supports direct addressing, no I2C
+ * @note        The driver currently supports both direct addressing
+ *              and I2C if the [PCF857X module](@ref drivers_pcf857x) is used
  *
  * @{
  *

tests/drivers/hd44780/README.md

@@ -4,6 +4,9 @@ This is a test application for the HD44780 LCD driver. This display comes with
 many Arduino starter kits under the name of LCM1602C, and typically has 16x2
 columns and rows.
 
+This examples covers the parallel mode of the HD44780 driver. For the I2C mode,
+please refer to `tests/drivers/hd44780_i2c`.
+
 # Details
 
 This test application will initialize the HD44780 driver with the configuration

tests/drivers/hd44780_i2c/Makefile

@@ -0,0 +1,28 @@
+include ../Makefile.drivers_common
+
+USEMODULE += hd44780
+
+# The I2C versions of this display usually use an I2C port expander
+# such as the PCF8574, PCF8574A or PCF8575. Depending on the
+# board variant, the port expander can also have different
+# I2C addresses. Typical ranges are:
+#   PCF8574  - 0x20 to 0x27
+#   PCF8574A - 0x38 to 0x3F
+#   PCF8475  - 0x20 to 0x27
+DRIVER ?= pcf8574
+ADDRESS ?= 0x20
+
+# select the right module and calculate the I2C address offset
+ifeq (pcf8574,$(DRIVER))
+  CFLAGS += -D"PCF857X_PARAM_ADDR=($(ADDRESS)-PCF8574_BASE_ADDR)"
+else ifeq (pcf8574a,$(DRIVER))
+  CFLAGS += -D"PCF857X_PARAM_ADDR=($(ADDRESS)-PCF8574A_BASE_ADDR)"
+else ifeq (pcf8575,$(DRIVER))
+  CFLAGS += -D"PCF857X_PARAM_ADDR=($(ADDRESS)-PCF8575_BASE_ADDR)"
+else
+  $(error Invalid I2C port expander selected: $(DRIVER))
+endif
+
+USEMODULE += $(DRIVER)
+
+include $(RIOTBASE)/Makefile.include

tests/drivers/hd44780_i2c/Makefile.ci

@@ -0,0 +1,3 @@
+BOARD_INSUFFICIENT_MEMORY := \
+    atmega8 \
+    #

tests/drivers/hd44780_i2c/README.md

@@ -0,0 +1,36 @@
+# About
+
+This is a test application for the HD44780 LCD driver. This display comes with
+many Arduino starter kits under the name of LCM1602C, and typically has 16x2
+columns and rows.
+
+This examples covers the I2C mode of the HD44780 driver. For the parallel mode,
+please refer to `tests/drivers/hd44780`.
+
+# Details
+
+This test application will initialize the HD44780 driver with the configuration
+as specified in the default `hd44780_params.h` file.
+
+The HD44780 compatible displays are often available with an I2C interface,
+which is realized with an I2C port expander connected to the parallel
+interface. Typically these I2C add-on boards feature a PCF8574(A) or PCF8575
+chip with selectable I2C addresses.
+ - PCF8574: Address Range from 0x20 to 0x27
+ - PCF8574A: Address Range from 0x38 to 0x3F
+ - PCF8575: Address Range from 0x20 to 0x27
+
+Please specify the chip present on your board and the according I2C address
+with a command such as this:
+
+```sh
+DRIVER=pcf8575 ADDRESS=0x27 BOARD=... make ...
+```
+
+This would select the PCF8575 IO expander with the I2C address 0x27.
+If no chip is selected, the build system sets the PCF8574 with address 0x20 as
+default.
+
+If you don't know which base address the board has, you can use the
+`tests/periph/i2c` test program and perform an I2C bus scan. This scan reveals
+all devices connected to the I2C bus and their respective addresses.

tests/drivers/hd44780_i2c/main.c

@@ -0,0 +1 @@
+../hd44780/main.c

tests/drivers/hd44780_i2c/tests-with-config/01-run.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+
+# Copyright (C) 2016 Kaspar Schleiser <kaspar@schleiser.de>
+#               2017 Sebastian Meiling <s@mlng.net>
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+import sys
+from testrunner import run
+
+
+def testfunc(child):
+    child.expect_exact("[START]")
+    child.expect_exact("[SUCCESS]")
+
+
+if __name__ == "__main__":
+    sys.exit(run(testfunc))