diff -r 000000000000 -r 88d965579617 components/u8g2/csrc/u8x8_byte.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/components/u8g2/csrc/u8x8_byte.c	Tue Oct 08 12:00:31 2019 +0200
@@ -0,0 +1,666 @@
+/*
+
+  u8x8_byte.c 
+  
+  Universal 8bit Graphics Library (https://github.com/olikraus/u8g2/)
+
+  Copyright (c) 2016, olikraus@gmail.com
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without modification, 
+  are permitted provided that the following conditions are met:
+
+  * Redistributions of source code must retain the above copyright notice, this list 
+    of conditions and the following disclaimer.
+    
+  * Redistributions in binary form must reproduce the above copyright notice, this 
+    list of conditions and the following disclaimer in the documentation and/or other 
+    materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 
+  CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, 
+  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
+  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
+  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 
+  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
+  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
+  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
+  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
+  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
+  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
+  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  
+  
+  
+*/
+
+#include "u8x8.h"
+
+uint8_t u8x8_byte_SetDC(u8x8_t *u8x8, uint8_t dc)
+{
+  return u8x8->byte_cb(u8x8, U8X8_MSG_BYTE_SET_DC, dc, NULL);
+}
+
+uint8_t u8x8_byte_SendBytes(u8x8_t *u8x8, uint8_t cnt, uint8_t *data)
+{
+  return u8x8->byte_cb(u8x8, U8X8_MSG_BYTE_SEND, cnt, (void *)data);
+}
+
+uint8_t u8x8_byte_SendByte(u8x8_t *u8x8, uint8_t byte)
+{
+  return u8x8_byte_SendBytes(u8x8, 1, &byte);
+}
+
+uint8_t u8x8_byte_StartTransfer(u8x8_t *u8x8)
+{
+  return u8x8->byte_cb(u8x8, U8X8_MSG_BYTE_START_TRANSFER, 0, NULL);
+}
+
+uint8_t u8x8_byte_EndTransfer(u8x8_t *u8x8)
+{
+  return u8x8->byte_cb(u8x8, U8X8_MSG_BYTE_END_TRANSFER, 0, NULL);
+}
+
+/*=========================================*/
+
+uint8_t u8x8_byte_empty(U8X8_UNUSED u8x8_t *u8x8, uint8_t msg, U8X8_UNUSED uint8_t arg_int, U8X8_UNUSED void *arg_ptr)
+{
+  switch(msg)
+  {
+    case U8X8_MSG_BYTE_SEND:
+    case U8X8_MSG_BYTE_INIT:
+    case U8X8_MSG_BYTE_SET_DC:
+    case U8X8_MSG_BYTE_START_TRANSFER:
+    case U8X8_MSG_BYTE_END_TRANSFER:
+      break;	/* do nothing */
+  }
+  return 1;	/* always succeed */
+}
+
+
+/*=========================================*/
+
+
+/*
+  Uses:
+    u8x8->display_info->sda_setup_time_ns
+    u8x8->display_info->sck_pulse_width_ns
+    u8x8->display_info->spi_mode
+    u8x8->display_info->chip_disable_level
+    u8x8->display_info->chip_enable_level
+    u8x8->display_info->post_chip_enable_wait_ns
+    u8x8->display_info->pre_chip_disable_wait_ns
+  Calls to GPIO and DELAY:
+    U8X8_MSG_DELAY_NANO
+    U8X8_MSG_GPIO_DC
+    U8X8_MSG_GPIO_CS
+    U8X8_MSG_GPIO_CLOCK
+    U8X8_MSG_GPIO_DATA
+  Handles:
+    U8X8_MSG_BYTE_INIT
+    U8X8_MSG_BYTE_SEND
+    U8X8_MSG_BYTE_SET_DC
+    U8X8_MSG_BYTE_START_TRANSFER
+    U8X8_MSG_BYTE_END_TRANSFER
+*/
+
+uint8_t u8x8_byte_4wire_sw_spi(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+  uint8_t i, b;
+  uint8_t *data;
+  uint8_t takeover_edge = u8x8_GetSPIClockPhase(u8x8);
+  uint8_t not_takeover_edge = 1 - takeover_edge;
+ 
+  switch(msg)
+  {
+    case U8X8_MSG_BYTE_SEND:
+      data = (uint8_t *)arg_ptr;
+      while( arg_int > 0 )
+      {
+	b = *data;
+	data++;
+	arg_int--;
+	for( i = 0; i < 8; i++ )
+	{
+	  if ( b & 128 )
+	    u8x8_gpio_SetSPIData(u8x8, 1);
+	  else
+	    u8x8_gpio_SetSPIData(u8x8, 0);
+	  b <<= 1;
+	  
+	  u8x8_gpio_SetSPIClock(u8x8, not_takeover_edge);
+	  u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->sda_setup_time_ns);
+	  u8x8_gpio_SetSPIClock(u8x8, takeover_edge);
+	  u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->sck_pulse_width_ns);
+	}    
+      }
+      break;
+      
+    case U8X8_MSG_BYTE_INIT:
+      /* disable chipselect */
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);
+      /* no wait required here */
+      
+      /* for SPI: setup correct level of the clock signal */
+      u8x8_gpio_SetSPIClock(u8x8, u8x8_GetSPIClockPhase(u8x8));
+      break;
+    case U8X8_MSG_BYTE_SET_DC:
+      u8x8_gpio_SetDC(u8x8, arg_int);
+      break;
+    case U8X8_MSG_BYTE_START_TRANSFER:
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_enable_level);  
+      u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->post_chip_enable_wait_ns, NULL);
+      break;
+    case U8X8_MSG_BYTE_END_TRANSFER:
+      u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->pre_chip_disable_wait_ns, NULL);
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);
+      break;
+    default:
+      return 0;
+  }
+  return 1;
+}
+
+/*=========================================*/
+
+uint8_t u8x8_byte_8bit_6800mode(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+  uint8_t i, b;
+  uint8_t *data;
+ 
+  switch(msg)
+  {
+    case U8X8_MSG_BYTE_SEND:
+      data = (uint8_t *)arg_ptr;
+      while( arg_int > 0 )
+      {
+	b = *data;
+	data++;
+	arg_int--;
+	for( i = U8X8_MSG_GPIO_D0; i <= U8X8_MSG_GPIO_D7; i++ )
+	{
+	  u8x8_gpio_call(u8x8, i, b&1);
+	  b >>= 1;
+	}    
+	
+	u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->data_setup_time_ns);
+	u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_E, 1);
+	u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->write_pulse_width_ns);
+	u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_E, 0);
+      }
+      break;
+      
+    case U8X8_MSG_BYTE_INIT:
+      /* disable chipselect */
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);    
+      /* ensure that the enable signal is high */
+      u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_E, 0);
+      break;
+    case U8X8_MSG_BYTE_SET_DC:
+      u8x8_gpio_SetDC(u8x8, arg_int);
+      break;
+    case U8X8_MSG_BYTE_START_TRANSFER:
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_enable_level);  
+      u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->post_chip_enable_wait_ns, NULL);
+      break;
+    case U8X8_MSG_BYTE_END_TRANSFER:
+      u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->pre_chip_disable_wait_ns, NULL);
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);
+      break;
+    default:
+      return 0;
+  }
+  return 1;
+}
+
+uint8_t u8x8_byte_8bit_8080mode(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+  uint8_t i, b;
+  uint8_t *data;
+ 
+  switch(msg)
+  {
+    case U8X8_MSG_BYTE_SEND:
+      data = (uint8_t *)arg_ptr;
+      while( arg_int > 0 )
+      {
+	b = *data;
+	data++;
+	arg_int--;
+	for( i = U8X8_MSG_GPIO_D0; i <= U8X8_MSG_GPIO_D7; i++ )
+	{
+	  u8x8_gpio_call(u8x8, i, b&1);
+	  b >>= 1;
+	}    
+	
+	u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->data_setup_time_ns);
+	u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_E, 0);
+	u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->write_pulse_width_ns);
+	u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_E, 1);
+      }
+      break;
+      
+    case U8X8_MSG_BYTE_INIT:
+      /* disable chipselect */
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);    
+      /* ensure that the enable signal is high */
+      u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_E, 1);
+      break;
+    case U8X8_MSG_BYTE_SET_DC:
+      u8x8_gpio_SetDC(u8x8, arg_int);
+      break;
+    case U8X8_MSG_BYTE_START_TRANSFER:
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_enable_level);  
+      u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->post_chip_enable_wait_ns, NULL);
+      break;
+    case U8X8_MSG_BYTE_END_TRANSFER:
+      u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->pre_chip_disable_wait_ns, NULL);
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);
+      break;
+    default:
+      return 0;
+  }
+  return 1;
+}
+
+/*=========================================*/
+
+uint8_t u8x8_byte_3wire_sw_spi(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+  uint8_t i;
+  uint8_t *data;
+  uint8_t takeover_edge = u8x8_GetSPIClockPhase(u8x8);
+  uint8_t not_takeover_edge = 1 - takeover_edge;
+  uint16_t b;
+  static uint8_t last_dc;
+ 
+  switch(msg)
+  {
+    case U8X8_MSG_BYTE_SEND:
+      data = (uint8_t *)arg_ptr;
+      while( arg_int > 0 )
+      {
+	b = *data;
+	if ( last_dc != 0 )
+	  b |= 256;
+	data++;
+	arg_int--;
+	for( i = 0; i < 9; i++ )
+	{
+	  if ( b & 256 )
+	    u8x8_gpio_SetSPIData(u8x8, 1);
+	  else
+	    u8x8_gpio_SetSPIData(u8x8, 0);
+	  b <<= 1;
+	  
+	  u8x8_gpio_SetSPIClock(u8x8, not_takeover_edge);
+	  u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->sda_setup_time_ns);
+	  u8x8_gpio_SetSPIClock(u8x8, takeover_edge);
+	  u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->sck_pulse_width_ns);
+	}    
+      }
+      break;
+      
+    case U8X8_MSG_BYTE_INIT:
+      /* disable chipselect */
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);
+      /* no wait required here */
+      
+      /* for SPI: setup correct level of the clock signal */
+      u8x8_gpio_SetSPIClock(u8x8, u8x8_GetSPIClockPhase(u8x8));
+      break;
+    case U8X8_MSG_BYTE_SET_DC:
+      last_dc = arg_int;
+      break;
+    case U8X8_MSG_BYTE_START_TRANSFER:
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_enable_level);  
+      u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->post_chip_enable_wait_ns, NULL);
+      break;
+    case U8X8_MSG_BYTE_END_TRANSFER:
+      u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->pre_chip_disable_wait_ns, NULL);
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);
+      break;
+    default:
+      return 0;
+  }
+  return 1;
+}
+
+/*=========================================*/
+
+void u8x8_byte_set_ks0108_cs(u8x8_t *u8x8, uint8_t arg)
+{
+  u8x8_gpio_SetCS(u8x8, arg&1);
+  arg = arg >> 1;
+  u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_CS1, arg&1);
+  arg = arg >> 1;
+  u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_CS2, arg&1);
+}
+
+/* 6800 mode */
+uint8_t u8x8_byte_ks0108(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+  uint8_t i, b;
+  uint8_t *data;
+ 
+  switch(msg)
+  {
+    case U8X8_MSG_BYTE_SEND:
+      data = (uint8_t *)arg_ptr;
+      while( arg_int > 0 )
+      {
+	b = *data;
+	data++;
+	arg_int--;
+	for( i = U8X8_MSG_GPIO_D0; i <= U8X8_MSG_GPIO_D7; i++ )
+	{
+	  u8x8_gpio_call(u8x8, i, b&1);
+	  b >>= 1;
+	}    
+	
+	u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->data_setup_time_ns);
+	u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_E, 1);
+	u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->write_pulse_width_ns);
+	u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_E, 0);
+      }
+      break;
+      
+    case U8X8_MSG_BYTE_INIT:
+      /* disable chipselect */
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);    
+      /* ensure that the enable signal is low */
+      u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_E, 0);
+      break;
+    case U8X8_MSG_BYTE_SET_DC:
+      u8x8_gpio_SetDC(u8x8, arg_int);
+      break;
+    case U8X8_MSG_BYTE_START_TRANSFER:
+      /* expects 3 bits in arg_int for the chip select lines */ 
+      u8x8_byte_set_ks0108_cs(u8x8, arg_int);
+      u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->post_chip_enable_wait_ns, NULL);
+      break;
+    case U8X8_MSG_BYTE_END_TRANSFER:
+      u8x8->gpio_and_delay_cb(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->pre_chip_disable_wait_ns, NULL);
+      u8x8_byte_set_ks0108_cs(u8x8, arg_int);
+      break;
+    default:
+      return 0;
+  }
+  return 1;
+}
+
+
+/* sed1520 or sbn1661 
+  U8X8_MSG_GPIO_E --> E1
+  U8X8_MSG_GPIO_CS --> E2
+*/
+uint8_t u8x8_byte_sed1520(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+  uint8_t i, b;
+  uint8_t *data;
+  static uint8_t enable_pin;
+ 
+  switch(msg)
+  {
+    case U8X8_MSG_BYTE_SEND:
+      data = (uint8_t *)arg_ptr;
+      while( arg_int > 0 )
+      {
+	b = *data;
+	data++;
+	arg_int--;
+	for( i = U8X8_MSG_GPIO_D0; i <= U8X8_MSG_GPIO_D7; i++ )
+	{
+	  u8x8_gpio_call(u8x8, i, b&1);
+	  b >>= 1;
+	}    
+	
+	u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->data_setup_time_ns);
+	u8x8_gpio_call(u8x8, enable_pin, 1);
+	u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, 200);		/* KS0108 requires 450 ns, use 200 here */
+	u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_NANO, u8x8->display_info->write_pulse_width_ns);  /* expect 250 here */
+	u8x8_gpio_call(u8x8, enable_pin, 0);
+      }
+      break;
+      
+    case U8X8_MSG_BYTE_INIT:
+      /* disable chipselect */
+      u8x8_gpio_SetCS(u8x8, u8x8->display_info->chip_disable_level);    
+      /* ensure that the enable signals are low */
+      u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_E, 0);
+      u8x8_gpio_call(u8x8, U8X8_MSG_GPIO_CS, 0);
+      enable_pin = U8X8_MSG_GPIO_E;
+      break;
+    case U8X8_MSG_BYTE_SET_DC:
+      u8x8_gpio_SetDC(u8x8, arg_int);
+      break;
+    case U8X8_MSG_BYTE_START_TRANSFER:
+      /* cs lines are not supported for the SED1520/SBN1661 */
+      /* instead, this will select the E1 or E2 line */ 
+      enable_pin = U8X8_MSG_GPIO_E;
+      if ( arg_int != 0 )
+	enable_pin = U8X8_MSG_GPIO_CS;
+      break;
+    case U8X8_MSG_BYTE_END_TRANSFER:
+      break;
+    default:
+      return 0;
+  }
+  return 1;
+}
+
+/*=========================================*/
+
+
+/*
+  software i2c,
+  ignores ACK response (which is anyway not provided by some displays)
+  also does not allow reading from the device
+*/
+static void i2c_delay(u8x8_t *u8x8) U8X8_NOINLINE;
+static void i2c_delay(u8x8_t *u8x8)
+{
+  //u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_10MICRO, u8x8->display_info->i2c_bus_clock_100kHz);
+  u8x8_gpio_Delay(u8x8, U8X8_MSG_DELAY_I2C, u8x8->display_info->i2c_bus_clock_100kHz);
+}
+
+static void i2c_init(u8x8_t *u8x8)
+{
+  u8x8_gpio_SetI2CClock(u8x8, 1);
+  u8x8_gpio_SetI2CData(u8x8, 1);
+  
+  i2c_delay(u8x8);
+}
+
+/* actually, the scl line is not observed, so this procedure does not return a value */
+
+static void i2c_read_scl_and_delay(u8x8_t *u8x8)
+{
+  /* set as input (line will be high) */
+  u8x8_gpio_SetI2CClock(u8x8, 1);
+
+  i2c_delay(u8x8);
+}
+
+static void i2c_clear_scl(u8x8_t *u8x8)
+{
+  u8x8_gpio_SetI2CClock(u8x8, 0);
+}
+
+static void i2c_read_sda(u8x8_t *u8x8)
+{
+  /* set as input (line will be high) */
+  u8x8_gpio_SetI2CData(u8x8, 1);
+}
+
+static void i2c_clear_sda(u8x8_t *u8x8)
+{
+  /* set open collector and drive low */
+  u8x8_gpio_SetI2CData(u8x8, 0);
+}
+
+static void i2c_start(u8x8_t *u8x8)
+{
+  if ( u8x8->i2c_started != 0 )
+  {
+    /* if already started: do restart */
+    i2c_read_sda(u8x8);     /* SDA = 1 */
+    i2c_delay(u8x8);
+    i2c_read_scl_and_delay(u8x8);
+  }
+  i2c_read_sda(u8x8);
+  /* send the start condition, both lines go from 1 to 0 */
+  i2c_clear_sda(u8x8);
+  i2c_delay(u8x8);
+  i2c_clear_scl(u8x8);
+  u8x8->i2c_started = 1;
+}
+
+
+static void i2c_stop(u8x8_t *u8x8)
+{
+  /* set SDA to 0 */
+  i2c_clear_sda(u8x8);  
+  i2c_delay(u8x8);
+ 
+  /* now release all lines */
+  i2c_read_scl_and_delay(u8x8);
+ 
+  /* set SDA to 1 */
+  i2c_read_sda(u8x8);
+  i2c_delay(u8x8);
+  u8x8->i2c_started = 0;
+}
+
+static void i2c_write_bit(u8x8_t *u8x8, uint8_t val)
+{
+  if (val)
+    i2c_read_sda(u8x8);
+  else
+    i2c_clear_sda(u8x8);
+ 
+  i2c_delay(u8x8);
+  i2c_read_scl_and_delay(u8x8);
+  i2c_clear_scl(u8x8);
+}
+
+static void i2c_read_bit(u8x8_t *u8x8)
+{
+  //uint8_t val;
+  /* do not drive SDA */
+  i2c_read_sda(u8x8);
+  i2c_delay(u8x8);
+  i2c_read_scl_and_delay(u8x8);
+  i2c_read_sda(u8x8);
+  i2c_delay(u8x8);
+  i2c_clear_scl(u8x8);
+  //return val;
+}
+
+static void i2c_write_byte(u8x8_t *u8x8, uint8_t b)
+{
+  i2c_write_bit(u8x8, b & 128);
+  i2c_write_bit(u8x8, b & 64);
+  i2c_write_bit(u8x8, b & 32);
+  i2c_write_bit(u8x8, b & 16);
+  i2c_write_bit(u8x8, b & 8);
+  i2c_write_bit(u8x8, b & 4);
+  i2c_write_bit(u8x8, b & 2);
+  i2c_write_bit(u8x8, b & 1);
+    
+  /* read ack from client */
+  /* 0: ack was given by client */
+  /* 1: nothing happend during ack cycle */  
+  i2c_read_bit(u8x8);
+}
+
+uint8_t u8x8_byte_sw_i2c(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+  uint8_t *data;
+
+  switch(msg)
+  {
+    case U8X8_MSG_BYTE_SEND:
+      data = (uint8_t *)arg_ptr;
+    
+      while( arg_int > 0 )
+      {
+	i2c_write_byte(u8x8, *data);
+	data++;
+	arg_int--;
+      }
+      
+      break;
+      
+    case U8X8_MSG_BYTE_INIT:
+      i2c_init(u8x8);
+      break;
+    case U8X8_MSG_BYTE_SET_DC:
+      break;
+    case U8X8_MSG_BYTE_START_TRANSFER:
+      i2c_start(u8x8);
+      i2c_write_byte(u8x8, u8x8_GetI2CAddress(u8x8));
+      //i2c_write_byte(u8x8, 0x078);
+      break;
+    case U8X8_MSG_BYTE_END_TRANSFER:
+      i2c_stop(u8x8);
+      break;
+    default:
+      return 0;
+  }
+  return 1;
+}
+
+/*=========================================*/
+
+/* alternative i2c byte procedure */
+#ifdef ALTERNATIVE_I2C_BYTE_PROCEDURE
+
+
+void i2c_transfer(u8x8_t *u8x8, uint8_t adr, uint8_t cnt, uint8_t *data)
+{
+  uint8_t i;
+  i2c_start(u8x8);
+  i2c_write_byte(u8x8, adr);
+  for( i = 0; i < cnt; i++ )
+    i2c_write_byte(u8x8, data[i]);
+  i2c_stop(u8x8);  
+}
+
+
+uint8_t u8x8_byte_sw_i2c(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
+{
+  static uint8_t buffer[32];		/* u8g2/u8x8 will never send more than 32 bytes */
+  static uint8_t buf_idx;
+  uint8_t *data;
+ 
+  switch(msg)
+  {
+    case U8X8_MSG_BYTE_SEND:
+      data = (uint8_t *)arg_ptr;      
+      while( arg_int > 0 )
+      {
+	buffer[buf_idx++] = *data;
+	data++;
+	arg_int--;
+      }      
+      break;
+    case U8X8_MSG_BYTE_INIT:
+      i2c_init(u8x8);			/* init i2c communication */
+      break;
+    case U8X8_MSG_BYTE_SET_DC:
+      /* ignored for i2c */
+      break;
+    case U8X8_MSG_BYTE_START_TRANSFER:
+      buf_idx = 0;
+      break;
+    case U8X8_MSG_BYTE_END_TRANSFER:
+      i2c_transfer(u8x8, u8x8_GetI2CAddress(u8x8), buf_idx, buffer);
+      break;
+    default:
+      return 0;
+  }
+  return 1;
+}
+
+#endif