diff --git a/libraries/TLC5917/CHANGELOG.md b/libraries/TLC5917/CHANGELOG.md
index 68be5355..822c25b4 100644
--- a/libraries/TLC5917/CHANGELOG.md
+++ b/libraries/TLC5917/CHANGELOG.md
@@ -6,6 +6,21 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.1.2] - 2024-06-02
+- add **TLC5917_NORMAL_MODE** and **TLC5917_SPECIAL_MODE**
+- add **uint8_t getMode()**
+- rename setCurrentAdjustMode() to **void setSpecialMode()**
+- rename **getChannels()** into **channelCount()** (looked like getChannel)
+- refactored **writeConfiguration()**
+- add **uint8_t getConfiguration()**
+- add **bool setGain(bool CM, bool HC, uint8_t CC)**
+- add **bool setCurrentGain(float n)**
+- add **float getVoltageGain()**
+- add **float getCurrentGain()**
+- update readme.md
+- add / update examples.
+- minor edits.
+
 ## [0.1.1] - 2024-06-02
 - fix **setChannel()**
 - rename **getChannels()** to **channelCount()**
@@ -13,7 +28,6 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - update readme.md
 - minor edits
 
-
 ## [0.1.0] - 2024-03-17
 - initial version
 
diff --git a/libraries/TLC5917/README.md b/libraries/TLC5917/README.md
index 96eaf3a3..f8cf1411 100644
--- a/libraries/TLC5917/README.md
+++ b/libraries/TLC5917/README.md
@@ -18,14 +18,17 @@ TLC5917 is an Arduino library for TLC5917 8-Channel Constant-Current LED Sink Dr
 
 **Experimental**
 
-This library allows control over the 8 channels of a TLC5917 device.
+The **TLC5917** library allows control over the 8 channels (outputs) of a TLC5917 device.
+This library also support more than one device in a daisy chain (see below).
 
-The library allows to set outputs individually or a group in one call.
+The library allows to set the channels (outputs) individually or a group in one call.
+Furthermore it allows to set a current gain for all devices connected.
 
-The TLC5916 is a derived class that is functional identical to the TLC5917 (for now).
-When implementation proceeds this might change.
+The **TLC5916** is a derived class that is functional identical to the TLC5917 (for now).
+When implementation proceeds this might change, the difference is in support for fetching 
+the status and error modi. This is not supported by the library
 
-The library is **experimental** and needs more testing with hardware.  
+The library needs more testing with hardware.  
 Please share your experiences.
 
 (Changes of the interface are definitely possible).
@@ -33,7 +36,7 @@ Please share your experiences.
 
 #### Daisy chaining
 
-This library supports daisy chaining.
+This library supports daisy chaining of TLC5917 modules.
 A constructor takes the number of devices as parameter and 
 an internal buffer is allocated (8 elements per device).
 This internal buffer is clocked into the devices with **write()**.
@@ -65,7 +68,7 @@ The blank pin is explained in more detail below.
 To be used for multiple devices, typical 2 or more.
 Defines the pins used for uploading / writing the PWM data to the module.
 The blank pin is explained in more detail below. 
-- **~TLC5917()** destructor
+- **~TLC5917()** destructor. Frees the allocated memory.
 
 #### Base
 
@@ -73,8 +76,7 @@ The blank pin is explained in more detail below.
 The TLC is disabled by default, as the device has random values in its grey-scale register. 
 One must call **enable()** explicitly.
 - **int channelCount()** return the amount of channels == 8 x number of devices.
-- **int getChannels()** return the amount of channels == 8 x number of devices.
-Will be obsolete in 0.2.0.
+
 
 #### Set/Get channels
 
@@ -85,16 +87,16 @@ The user has to take care the the size of array holds the right amount of bytes.
 - **bool setAll(bool on)** set all channels on or off.
 - **bool getChannel(uint8_t channel)** get current state of a channel in the cached buffer.
 - **void write()** writes the whole buffer (deviceCount x 8 values) to the device(s).
-- **void write(int n)** writes a part of the buffer (only **n** values) to the device.
+- **void write(int n)** writes a part of the internal buffer (only **n** values) to the device.
 Typical used to speed up if less than max number e.g. only 17 channels are used
 and needs to be updated.  
 **experimental, might have side effects**
 
 
 **write()** must be called after setting all values one wants to change.
-Doing that per channel is far less efficient if one wants to update multiple 
+Updating per channel is possible but far less efficient if one has to update multiple 
 channels as fast as possible.
-See also **TLC5917_performance.ino** for an indication of time.
+See also **TLC5917_performance.ino** for an indication of time needed.
 
 
 #### Blank line  TODO CHECK
@@ -115,37 +117,61 @@ a separate **enable()** per device you might need to connect the devices
 "in parallel" instead of "in series" (daisy chained).
 The blank parameter in the constructor should be set to -1 (out of range value).
 
+It might be possible to use a PWM pin on the OE line to dim the LEDS.
+This is neither tested or supported by the library.
+
 
 #### Configure gain
 
 See datasheet page 23 for details.
 
-- **void setCurrentAdjustMode()**
-- **void setNormalMode()**
-- **void writeConfiguration(uint8_t config)** See page 23 datasheet
+- **void setNormalMode()**  to send the data for the LEDS.
+- **void setSpecialMode()**  to configure the gain.
+
+
+The special mode needs to be set for the following functions:
+
+- **void writeConfiguration(uint8_t configuration)** See page 23 datasheet.
+Writes same configuration to all devices. One must call setSpecialMode() first
+and setNormalMode() after..
+- **uint8_t getConfiguration()** returns last written configuration 
+bit mask (from cache).
+- **bool setGain(bool CM, bool HC, uint8_t CC)**  CC = {0..63}
+returns false if CC >= 64
+- **bool setCurrentGain(float n)** n = 0.250 - 3.000 (nicer range).  
+Over the range 0.250 - 2.989 the max error is 0.0124  
+Over the range 2.989 - 3.000 the max error goes up to 0.023  
+So except for end of the range the error is (IMHO) small.
+Returns false if out of range (n < 0.250 or n > 3.0).  
+- **float getVoltageGain()** see below (from cache).
+- **float getCurrentGain()** see below (from cache).
+
 
 |      bit  |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |
 |:---------:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|
-|  meaning  |  CM |  HC | CC0 | CC1 | CC2 | CC3 | CC4 | CC5 |
+|  abbrev   |  CM |  HC | CC0 | CC1 | CC2 | CC3 | CC4 | CC5 |
 |  default  |  1  |  1  |  1  |  1  |  1  |  1  |  1  |  1  |
 
-CM limits the output current range.  
-- High Current Multiplier (CM = 1): 10 mA to 120 mA.
-- Low Current Multiplier  (CM = 0):  3 mA to  40 mA.
+CM == Current Multiplier
+- limits the output current range.  
+- Low  (CM = 0):  3 mA to  40 mA.
+- High (CM = 1): 10 mA to 120 mA.  == CM(0) x 3
 
 VG (voltage gain) = (1 + HC) × (1 + D/64) / 4
-where  D = CC0 × 32 + CC1 × 16 + CC2 × 8 + CC3 × 4 + CC4 × 2 + CC5
+
+where  D = CC0 × 32 + CC1 × 16 + CC2 × 8 + CC3 × 4 + CC4 × 2 + CC5  
+       D = 0..63
 
 CG (current gain) = VG x pow(3, CM - 1)    
 
 ```
 Default 
-CG = VG x 3;  
-VG = 2 x ( 1 + 63/64) / 4 = 127/128
+VG = 2 x ( 1 + 63/64) / 4 = 127/128  
+CG = VG x 3 = ~2.977
 ```
 
-TODO test with hardware to understand this in detail.  
-Actual current depends on Rext (see datasheet).
+TODO: test with hardware to understand this in detail.  
+Actual current depends on Rext == external resistor (see datasheet).
 
 
 ## Performance
@@ -159,24 +185,28 @@ See **TLC5917_performance.ino** for an indicative test.
 
 - update documentation
 - buy hardware
-  - test test test 
-- get basic functionality running
+  - test test test
 
 #### Should
 
-- get basic functionality running
 - investigate daisy chaining. (hardware needed).
   - max CLOCK speed when chained (50% DutyCycle)
   - what is clock in practice (e.g. an ESP32 240 MHz)
+- now the CurrentGain is set to the same value for all devices.
+  - needs array, one value (uint8_t or float) per device, investigate.
 
 #### Could
 
-- add examples
-- **void getChannel(uint8_t array)** fill array with current data
-- **index operator []** to set channels?
+- **index operator []** to get set channels, might be better?
+- reading error codes from SDO
 
+#### Wont (unless needed)
 
-#### Wont
+- **void getChannel(uint8_t array)** fill an array with current data.
+- error handling in special mode
+  - over-temperature, open-load, short to GND, short to VLED (5917 only).
+- investigate if hardware SPI is possible
+  - which mode?
 
 
 ## Support
diff --git a/libraries/TLC5917/TLC5917.cpp b/libraries/TLC5917/TLC5917.cpp
index d297b0a2..0b8a0916 100644
--- a/libraries/TLC5917/TLC5917.cpp
+++ b/libraries/TLC5917/TLC5917.cpp
@@ -1,7 +1,7 @@
 //
 //    FILE: TLC5917.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.1
+// VERSION: 0.1.2
 //    DATE: 2024-03-17
 // PURPOSE: Arduino library for TLC5917 8-Channel Constant-Current LED Sink Drivers.
 //     URL: https://github.com/RobTillaart/TLC5917
@@ -24,7 +24,9 @@ TLC5917::TLC5917(int deviceCount, uint8_t clock, uint8_t data, uint8_t LE, uint8
   _data   = data;
   _le     = LE;
   _oe     = OE;
+  _mode   = TLC5917_NORMAL_MODE;
   _buffer = (uint8_t *) calloc(_channelCount, sizeof(uint8_t));
+  _configuration = 0xFF;  //  page 23  datasheet
 }
 
 
@@ -54,17 +56,13 @@ int TLC5917::channelCount()
   return _channelCount;
 }
 
-int TLC5917::getChannels()  //  OBSOLETE
-{
-  return _channelCount;
-}
-
 
 bool TLC5917::setChannel(uint8_t channel, bool on)
 {
   if (channel >= _channelCount) return false;
-  if (on) _buffer[channel / 8] |=  (1 << (channel & 0x07));
-  else    _buffer[channel / 8] &= ~(1 << (channel & 0x07));
+  uint8_t mask = 1 << (channel & 0x07);
+  if (on) _buffer[channel / 8] |=  mask;
+  else    _buffer[channel / 8] &= ~mask;
   return true;
 }
 
@@ -93,7 +91,8 @@ bool TLC5917::setAll(bool on)
 bool TLC5917::getChannel(uint8_t channel)
 {
   if (channel >= _channelCount) return false;
-  return (_buffer[channel / 8] & (1 << (channel & 0x07))) > 0;
+  uint8_t mask = 1 << (channel & 0x07);
+  return (_buffer[channel / 8] & mask) > 0;
 }
 
 
@@ -114,6 +113,7 @@ void TLC5917::write(int chan)
   if (chan > _channelCount) chan = _channelCount;
   if (chan < 0) return;
 
+
 #if defined(ARDUINO_ARCH_AVR) || defined(ARDUINO_ARCH_MEGAAVR)
 
   //  register level optimized AVR
@@ -131,19 +131,18 @@ void TLC5917::write(int chan)
   {
     for (uint8_t mask = 0x80;  mask; mask >>= 1)
     {
-      *_clockRegister &= cbmask2;
       if (_buffer[channel] & mask)
       {
-        *_dataOutRegister |= outmask1;
+        *_dataOutRegister |= outmask1;  //  digitalWrite(_dat, HIGH);
       }
       else
       {
-        *_dataOutRegister &= outmask2;
+        *_dataOutRegister &= outmask2;  //  digitalWrite(_dat, LOW);
       }
-      *_clockRegister |= cbmask1;
+      *_clockRegister |= cbmask1;  //  digitalWrite(_clk, HIGH);
+      *_clockRegister &= cbmask2;  //  digitalWrite(_clk, LOW);
     }
   }
-  *_clockRegister &= cbmask2;
 
 #else
 
@@ -157,12 +156,11 @@ void TLC5917::write(int chan)
   {
     for (uint8_t mask = 0x80;  mask; mask >>= 1)
     {
-      digitalWrite(_clk, LOW);
       digitalWrite(_dat, _buffer[channel] & mask ? HIGH : LOW);
       digitalWrite(_clk, HIGH);
+      digitalWrite(_clk, LOW);
     }
   }
-  digitalWrite(_clk, LOW);
 
 #endif
 
@@ -201,7 +199,7 @@ bool TLC5917::isEnabled()
 //  NOT OPTIMIZED
 //
 //  Page 19
-void TLC5917::setCurrentAdjustMode()
+void TLC5917::setSpecialMode()
 {
   digitalWrite(_le, LOW);
   digitalWrite(_oe, HIGH);
@@ -224,6 +222,8 @@ void TLC5917::setCurrentAdjustMode()
   digitalWrite(_le, LOW);
   digitalWrite(_clock, HIGH);
   digitalWrite(_clock, LOW);
+
+  _mode = TLC5917_SPECIAL_MODE;
 }
 
 
@@ -248,34 +248,117 @@ void TLC5917::setNormalMode()
 
   digitalWrite(_clock, HIGH);
   digitalWrite(_clock, LOW);
+
+  _mode = TLC5917_NORMAL_MODE;
 }
 
 
-void TLC5917::writeConfiguration(uint8_t config)
+uint8_t TLC5917::getMode()
+{
+  return _mode;
+}
+
+
+//  9.4.3 Writing Configuration Code in Special Mode
+void TLC5917::writeConfiguration(uint8_t configuration)
 {
   uint8_t _clk = _clock;
   uint8_t _dat = _data;
-  uint8_t _devices = _channelCount/8;
+  uint8_t _devices = _channelCount / 8;
 
   //  write same configuration to all devices
   for (int i = 0; i < _devices; i++)
   {
-    for (uint8_t mask = 0x80;  mask; mask >>= 1)
+    //  handle bit 7- 1
+    for (uint8_t mask = 0x80;  mask > 1; mask >>= 1)
     {
-      digitalWrite(_clk, LOW);
-      digitalWrite(_dat, config & mask ? HIGH : LOW);
+      digitalWrite(_dat, configuration & mask ? HIGH : LOW);
       digitalWrite(_clk, HIGH);
+      digitalWrite(_clk, LOW);
     }
+    //  bit 0 should have an LE pulse
+    digitalWrite(_le, HIGH);
+    digitalWrite(_dat, configuration & 0x01 ? HIGH : LOW);
+    digitalWrite(_clk, HIGH);
     digitalWrite(_clk, LOW);
+    digitalWrite(_le, LOW);
   }
-
-  //  pulse latch to hold the signals in configuration register.
-  //  not exactly like Page 18 figure 13.
-  digitalWrite(_le, HIGH);
-  digitalWrite(_le, LOW);
+  _configuration = configuration;
 }
 
 
+uint8_t TLC5917::getConfiguration()
+{
+  return _configuration;
+}
+
+
+//  Page 23
+bool TLC5917::setGain(bool CM, bool HC, uint8_t CC)
+{
+  if (CC > 63) return false;
+  _configuration = CC;
+  if (CM) _configuration |= 0x80;
+  if (HC) _configuration |= 0x40;
+  writeConfiguration(_configuration);
+  return true;
+}
+
+
+float TLC5917::getVoltageGain()
+{
+  uint8_t CC = _configuration & 0x3F;  //  0..63
+  uint8_t HC = (_configuration & 0x40) ? 1 : 0;
+  float VG = (1.0 + HC) * (1.0 + CC * 0.015625) / 4;  //  0.015625 = 1/64
+  return VG;
+}
+
+
+float TLC5917::getCurrentGain()
+{
+  float CG = getVoltageGain();
+  // uint8_t CM = _configuration & 0x80;
+  if (_configuration & 0x80) CG *= 3;
+  return CG;
+}
+
+
+bool TLC5917::setCurrentGain(float n)
+{
+  if (n < 0.250) return false;
+  if (n > 3.000) return false;
+
+  uint8_t CM = 0;
+  uint8_t HC = 0;
+  uint8_t CC = 0;
+
+  //  n == (1 + HC) × (1 + D/64) / 4 * pow(3, CM - 1);
+  //  handle CM=1: values 1.0 - 2.977 == 150 - 255
+  //  note values 128 - 149 not used (twice in table)
+  if (n >= 1.0)
+  {
+    CM = 1;
+    n /= 3;
+  }
+  //  n == (1 + HC) × (1 + D/64) / 4
+  //  handle HC=1: values 0.5 - 1.0 == 64 - 127
+  if (n >= 0.5)
+  {
+    HC = 1;
+    n /= 2;
+  }
+
+  //  n == (1 + CC/64)/4;
+  //  values 0.25 - 0.5
+  n *= 4;
+  n -= 1;
+  if (n < 0) n = 0;
+  CC = round(n * 64);
+  if (CC >= 64) CC = 63;  //  truncate at top.
+  setGain(CM, HC, CC);
+  return true;
+}
+
 
 /////////////////////////////////////////////////////////////
 //
diff --git a/libraries/TLC5917/TLC5917.h b/libraries/TLC5917/TLC5917.h
index 889d1627..5fa030f0 100644
--- a/libraries/TLC5917/TLC5917.h
+++ b/libraries/TLC5917/TLC5917.h
@@ -2,13 +2,13 @@
 //
 //    FILE: TLC5917.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.1
+// VERSION: 0.1.2
 //    DATE: 2024-03-17
 // PURPOSE: Arduino library for TLC5917 8-Channel Constant-Current LED Sink Drivers.
 //     URL: https://github.com/RobTillaart/TLC5917
 
 
-#define TLC5917_LIB_VERSION             (F("0.1.1"))
+#define TLC5917_LIB_VERSION             (F("0.1.2"))
 
 
 #include "Arduino.h"
@@ -28,8 +28,11 @@
 #define OUTPUT  0
 */
 
-#define  TLC5917_OK                     0x0000
-#define  TLC5917_CHANNEL_ERROR          0xFFFF
+#define TLC5917_OK                      0x0000
+#define TLC5917_CHANNEL_ERROR           0xFFFF
+
+#define TLC5917_NORMAL_MODE             0x00
+#define TLC5917_SPECIAL_MODE            0x01
 
 
 class TLC5917
@@ -42,38 +45,50 @@ public:
   virtual ~TLC5917();
 
   bool     begin();
-  int      channelCount();  //  replaces getChannels which looks too much like getChannel.
-  int      getChannels();  //  will be obsolete in 0.2.0
+  int      channelCount();
 
   bool     setChannel(uint8_t channel, bool on);
-  bool     setChannel(uint8_t * array);  //  size must be deviceCount.
+  //       size array must be equal or larger than deviceCount.
+  bool     setChannel(uint8_t * array);
   bool     setAll(bool on);
   bool     getChannel(uint8_t channel);
 
-  //  write the buffer to the TLC5917 device(s).
+  //       write the buffer to the TLC5917 device(s).
   void     write(int n);
   void     write();
 
-  //  control the blank (OE) line.
+  //       control the blank (OE) line.
   void     enable();
   void     disable();
   bool     isEnabled();  //  returns status
 
-  //  configuration mode
-  //  TODO test if this works for single device.
-  //  TODO test if this works for cascaded devices.
-  void     setCurrentAdjustMode();
+  //       GAIN configuration mode
+  //       TODO test if this works for single device.
+  //       TODO test if this works for cascaded devices.
+  void     setSpecialMode();
   void     setNormalMode();
-  void     writeConfiguration(uint8_t config);
+  uint8_t  getMode();
+
+  //       writes the same configuration to all devices.
+  void     writeConfiguration(uint8_t configuration);
+  uint8_t  getConfiguration();
+  bool     setGain(bool CM, bool HC, uint8_t CC);  //  CC 0..63
+  bool     setCurrentGain(float n);  //  n = 0.250 - 3.000
+  float    getVoltageGain();
+  float    getCurrentGain();
 
 
 protected:
   int       _channelCount;
   uint8_t * _buffer;
+
   uint8_t   _clock;
   uint8_t   _data;
   uint8_t   _le;  //  latch enable
   uint8_t   _oe;  //  output enable
+
+  uint8_t   _mode;
+  uint8_t   _configuration;
 };
 
 
diff --git a/libraries/TLC5917/examples/TLC5917_NightRider/TLC5917_NightRider.ino b/libraries/TLC5917/examples/TLC5917_NightRider/TLC5917_NightRider.ino
index c884de49..67918539 100644
--- a/libraries/TLC5917/examples/TLC5917_NightRider/TLC5917_NightRider.ino
+++ b/libraries/TLC5917/examples/TLC5917_NightRider/TLC5917_NightRider.ino
@@ -1,7 +1,7 @@
 //
 //      FILE: TLC5917_NightRider.ino
 //    AUTHOR: Rob Tillaart
-//   PURPOSE: demo
+//   PURPOSE: demo running leds.
 //       URL: https://github.com/RobTillaart/TLC5917
 
 
@@ -24,7 +24,11 @@ void setup()
   Serial.print("TLC5917_LIB_VERSION: \t");
   Serial.println(TLC5917_LIB_VERSION);
 
-  tlc.begin();
+  if (tlc.begin() == false)
+  {
+    Serial.println("error");
+    while (1);
+  }
   tlc.enable();
 }
 
diff --git a/libraries/TLC5917/examples/TLC5917_demo/TLC5917_demo.ino b/libraries/TLC5917/examples/TLC5917_demo/TLC5917_demo.ino
index 4f76a2fa..54456d64 100644
--- a/libraries/TLC5917/examples/TLC5917_demo/TLC5917_demo.ino
+++ b/libraries/TLC5917/examples/TLC5917_demo/TLC5917_demo.ino
@@ -1,7 +1,7 @@
 //
 //    FILE: TLC5917_demo.ino
 //  AUTHOR: Rob Tillaart
-// PURPOSE: demo
+// PURPOSE: demo basic usage
 //     URL: https://github.com/RobTillaart/TLC5917
 
 
diff --git a/libraries/TLC5917/examples/TLC5917_demo_gain/TLC5917_demo_gain.ino b/libraries/TLC5917/examples/TLC5917_demo_gain/TLC5917_demo_gain.ino
new file mode 100644
index 00000000..3578f51a
--- /dev/null
+++ b/libraries/TLC5917/examples/TLC5917_demo_gain/TLC5917_demo_gain.ino
@@ -0,0 +1,87 @@
+//
+//    FILE: TLC5917_demo_gain.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: demo writeConfiguration() to set gain.
+//     URL: https://github.com/RobTillaart/TLC5917
+
+
+#include "TLC5917.h"
+
+
+const int DEVICES = 1;
+const int CLOCK = 13;
+const int DATA  = 12;
+const int LE    = 11;
+const int OE    = 10;
+
+TLC5917 tlc(DEVICES, CLOCK, DATA, LE, OE);
+
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("TLC5917_LIB_VERSION: \t");
+  Serial.println(TLC5917_LIB_VERSION);
+  Serial.println();
+
+  if (tlc.begin() == false)
+  {
+    Serial.println("error");
+    while (1);
+  }
+
+  Serial.print("Channels: ");
+  Serial.println(tlc.channelCount());
+
+  //  set all leds ON
+  tlc.enable();
+  for (int ch = 0; ch < tlc.channelCount(); ch++)
+  {
+    tlc.setChannel(ch, true);
+  }
+  tlc.write();
+
+  Serial.print("MODE:\t");
+  Serial.println(tlc.getMode());
+  tlc.setSpecialMode();
+  Serial.print("MODE:\t");
+  Serial.println(tlc.getMode());
+  uint32_t start = millis();
+  for (int conf = 0; conf < 256; conf++)
+  {
+    tlc.writeConfiguration(conf);
+    delay(100);
+  }
+  uint32_t stop = millis();
+  tlc.setNormalMode();
+  Serial.print("TIME:\t");
+  Serial.println(stop - start);
+  Serial.print("MODE:\t");
+  Serial.println(tlc.getMode());
+
+  Serial.println("\ndone...");
+
+  tlc.setSpecialMode();
+}
+
+
+void loop()
+{
+  //  increase gain
+  for (int conf = 0; conf < 256; conf++)
+  {
+    tlc.writeConfiguration(conf);
+    delay(10);
+  }
+  // decrease gain
+  for (int conf = 255; conf > 0; conf--)
+  {
+    tlc.writeConfiguration(conf);
+    delay(10);
+  }
+
+}
+
+
+//  -- END OF FILE --
diff --git a/libraries/TLC5917/examples/TLC5917_gain_table/TLC5917_gain_table.ino b/libraries/TLC5917/examples/TLC5917_gain_table/TLC5917_gain_table.ino
new file mode 100644
index 00000000..0018ac92
--- /dev/null
+++ b/libraries/TLC5917/examples/TLC5917_gain_table/TLC5917_gain_table.ino
@@ -0,0 +1,63 @@
+//
+//    FILE: TLC5917_gain_table.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: demo getCOnfiguration and getXXXGain()
+//          creates a table e.g. for Excel or plotter.
+//     URL: https://github.com/RobTillaart/TLC5917
+
+
+#include "TLC5917.h"
+
+
+const int DEVICES = 1;
+const int CLOCK = 13;
+const int DATA  = 12;
+const int LE    = 11;
+const int OE    = 10;
+
+TLC5917 tlc(DEVICES, CLOCK, DATA, LE, OE);
+
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("TLC5917_LIB_VERSION: \t");
+  Serial.println(TLC5917_LIB_VERSION);
+  Serial.println();
+
+  if (tlc.begin() == false)
+  {
+    Serial.println("error");
+    while (1);
+  }
+
+  tlc.setSpecialMode();
+
+  Serial.println("\tCONF\tVGAIN\tCGAIN");
+  for (int conf = 0; conf <= 255; conf++)
+  {
+    if (conf % 16 == 0) Serial.println();
+
+    tlc.writeConfiguration(conf);
+    Serial.print("\t");
+    //  comment next line for nice plotter view
+    Serial.print(tlc.getConfiguration());
+    Serial.print("\t");
+    Serial.print(tlc.getVoltageGain(), 3);
+    Serial.print("\t");
+    Serial.println(tlc.getCurrentGain(), 3);
+  }
+  Serial.println();
+
+  tlc.setNormalMode();
+  Serial.println("\ndone...");
+}
+
+
+void loop()
+{
+}
+
+
+//  -- END OF FILE --
diff --git a/libraries/TLC5917/examples/TLC5917_gain_table/TLC5917_gain_table.txt b/libraries/TLC5917/examples/TLC5917_gain_table/TLC5917_gain_table.txt
new file mode 100644
index 00000000..713911e1
--- /dev/null
+++ b/libraries/TLC5917/examples/TLC5917_gain_table/TLC5917_gain_table.txt
@@ -0,0 +1,280 @@
+TLC5917_gain_table.ino
+TLC5917_LIB_VERSION: 	0.1.2
+
+
+	CONF	VGAIN	CGAIN
+
+	0	0.250	0.250
+	1	0.254	0.254
+	2	0.258	0.258
+	3	0.262	0.262
+	4	0.266	0.266
+	5	0.270	0.270
+	6	0.273	0.273
+	7	0.277	0.277
+	8	0.281	0.281
+	9	0.285	0.285
+	10	0.289	0.289
+	11	0.293	0.293
+	12	0.297	0.297
+	13	0.301	0.301
+	14	0.305	0.305
+	15	0.309	0.309
+
+	16	0.312	0.312
+	17	0.316	0.316
+	18	0.320	0.320
+	19	0.324	0.324
+	20	0.328	0.328
+	21	0.332	0.332
+	22	0.336	0.336
+	23	0.340	0.340
+	24	0.344	0.344
+	25	0.348	0.348
+	26	0.352	0.352
+	27	0.355	0.355
+	28	0.359	0.359
+	29	0.363	0.363
+	30	0.367	0.367
+	31	0.371	0.371
+
+	32	0.375	0.375
+	33	0.379	0.379
+	34	0.383	0.383
+	35	0.387	0.387
+	36	0.391	0.391
+	37	0.395	0.395
+	38	0.398	0.398
+	39	0.402	0.402
+	40	0.406	0.406
+	41	0.410	0.410
+	42	0.414	0.414
+	43	0.418	0.418
+	44	0.422	0.422
+	45	0.426	0.426
+	46	0.430	0.430
+	47	0.434	0.434
+
+	48	0.438	0.438
+	49	0.441	0.441
+	50	0.445	0.445
+	51	0.449	0.449
+	52	0.453	0.453
+	53	0.457	0.457
+	54	0.461	0.461
+	55	0.465	0.465
+	56	0.469	0.469
+	57	0.473	0.473
+	58	0.477	0.477
+	59	0.480	0.480
+	60	0.484	0.484
+	61	0.488	0.488
+	62	0.492	0.492
+	63	0.496	0.496
+
+	64	0.500	0.500
+	65	0.508	0.508
+	66	0.516	0.516
+	67	0.523	0.523
+	68	0.531	0.531
+	69	0.539	0.539
+	70	0.547	0.547
+	71	0.555	0.555
+	72	0.563	0.563
+	73	0.570	0.570
+	74	0.578	0.578
+	75	0.586	0.586
+	76	0.594	0.594
+	77	0.602	0.602
+	78	0.609	0.609
+	79	0.617	0.617
+
+	80	0.625	0.625
+	81	0.633	0.633
+	82	0.641	0.641
+	83	0.648	0.648
+	84	0.656	0.656
+	85	0.664	0.664
+	86	0.672	0.672
+	87	0.680	0.680
+	88	0.688	0.688
+	89	0.695	0.695
+	90	0.703	0.703
+	91	0.711	0.711
+	92	0.719	0.719
+	93	0.727	0.727
+	94	0.734	0.734
+	95	0.742	0.742
+
+	96	0.750	0.750
+	97	0.758	0.758
+	98	0.766	0.766
+	99	0.773	0.773
+	100	0.781	0.781
+	101	0.789	0.789
+	102	0.797	0.797
+	103	0.805	0.805
+	104	0.813	0.813
+	105	0.820	0.820
+	106	0.828	0.828
+	107	0.836	0.836
+	108	0.844	0.844
+	109	0.852	0.852
+	110	0.859	0.859
+	111	0.867	0.867
+
+	112	0.875	0.875
+	113	0.883	0.883
+	114	0.891	0.891
+	115	0.898	0.898
+	116	0.906	0.906
+	117	0.914	0.914
+	118	0.922	0.922
+	119	0.930	0.930
+	120	0.938	0.938
+	121	0.945	0.945
+	122	0.953	0.953
+	123	0.961	0.961
+	124	0.969	0.969
+	125	0.977	0.977
+	126	0.984	0.984
+	127	0.992	0.992
+
+	128	0.250	0.750
+	129	0.254	0.762
+	130	0.258	0.773
+	131	0.262	0.785
+	132	0.266	0.797
+	133	0.270	0.809
+	134	0.273	0.820
+	135	0.277	0.832
+	136	0.281	0.844
+	137	0.285	0.855
+	138	0.289	0.867
+	139	0.293	0.879
+	140	0.297	0.891
+	141	0.301	0.902
+	142	0.305	0.914
+	143	0.309	0.926
+
+	144	0.312	0.938
+	145	0.316	0.949
+	146	0.320	0.961
+	147	0.324	0.973
+	148	0.328	0.984
+	149	0.332	0.996
+	150	0.336	1.008
+	151	0.340	1.020
+	152	0.344	1.031
+	153	0.348	1.043
+	154	0.352	1.055
+	155	0.355	1.066
+	156	0.359	1.078
+	157	0.363	1.090
+	158	0.367	1.102
+	159	0.371	1.113
+
+	160	0.375	1.125
+	161	0.379	1.137
+	162	0.383	1.148
+	163	0.387	1.160
+	164	0.391	1.172
+	165	0.395	1.184
+	166	0.398	1.195
+	167	0.402	1.207
+	168	0.406	1.219
+	169	0.410	1.230
+	170	0.414	1.242
+	171	0.418	1.254
+	172	0.422	1.266
+	173	0.426	1.277
+	174	0.430	1.289
+	175	0.434	1.301
+
+	176	0.438	1.312
+	177	0.441	1.324
+	178	0.445	1.336
+	179	0.449	1.348
+	180	0.453	1.359
+	181	0.457	1.371
+	182	0.461	1.383
+	183	0.465	1.395
+	184	0.469	1.406
+	185	0.473	1.418
+	186	0.477	1.430
+	187	0.480	1.441
+	188	0.484	1.453
+	189	0.488	1.465
+	190	0.492	1.477
+	191	0.496	1.488
+
+	192	0.500	1.500
+	193	0.508	1.523
+	194	0.516	1.547
+	195	0.523	1.570
+	196	0.531	1.594
+	197	0.539	1.617
+	198	0.547	1.641
+	199	0.555	1.664
+	200	0.563	1.687
+	201	0.570	1.711
+	202	0.578	1.734
+	203	0.586	1.758
+	204	0.594	1.781
+	205	0.602	1.805
+	206	0.609	1.828
+	207	0.617	1.852
+
+	208	0.625	1.875
+	209	0.633	1.898
+	210	0.641	1.922
+	211	0.648	1.945
+	212	0.656	1.969
+	213	0.664	1.992
+	214	0.672	2.016
+	215	0.680	2.039
+	216	0.688	2.062
+	217	0.695	2.086
+	218	0.703	2.109
+	219	0.711	2.133
+	220	0.719	2.156
+	221	0.727	2.180
+	222	0.734	2.203
+	223	0.742	2.227
+
+	224	0.750	2.250
+	225	0.758	2.273
+	226	0.766	2.297
+	227	0.773	2.320
+	228	0.781	2.344
+	229	0.789	2.367
+	230	0.797	2.391
+	231	0.805	2.414
+	232	0.813	2.437
+	233	0.820	2.461
+	234	0.828	2.484
+	235	0.836	2.508
+	236	0.844	2.531
+	237	0.852	2.555
+	238	0.859	2.578
+	239	0.867	2.602
+
+	240	0.875	2.625
+	241	0.883	2.648
+	242	0.891	2.672
+	243	0.898	2.695
+	244	0.906	2.719
+	245	0.914	2.742
+	246	0.922	2.766
+	247	0.930	2.789
+	248	0.938	2.812
+	249	0.945	2.836
+	250	0.953	2.859
+	251	0.961	2.883
+	252	0.969	2.906
+	253	0.977	2.930
+	254	0.984	2.953
+	255	0.992	2.977
+
+
+done...
diff --git a/libraries/TLC5917/examples/TLC5917_performance/performance_0.1.2.txt b/libraries/TLC5917/examples/TLC5917_performance/performance_0.1.2.txt
new file mode 100644
index 00000000..63ded1b5
--- /dev/null
+++ b/libraries/TLC5917/examples/TLC5917_performance/performance_0.1.2.txt
@@ -0,0 +1,25 @@
+Arduino UNO
+IDE: 1.8.19
+
+(AVR optimized write() on UNO)
+TLC5917_performance\TLC5917_performance.ino
+TLC5917_LIB_VERSION: 	0.1.2
+Channels:		800
+SETCHANNEL TRUE:	2572
+SETCHANNEL FALSE:	2848
+SETALL TRUE:		232
+WRITE:			14304
+
+Done...
+
+
+(default write() on UNO for reference)
+TLC5917_LIB_VERSION: 	0.1.2
+Channels:		800
+SETCHANNEL TRUE:	2572
+SETCHANNEL FALSE:	2848
+SETALL TRUE:		232
+WRITE:			75364
+
+Done...
+
diff --git a/libraries/TLC5917/examples/TLC5917_test_setCurrentGain/TLC5917_test_setCurrentGain.ino b/libraries/TLC5917/examples/TLC5917_test_setCurrentGain/TLC5917_test_setCurrentGain.ino
new file mode 100644
index 00000000..a48a4ce6
--- /dev/null
+++ b/libraries/TLC5917/examples/TLC5917_test_setCurrentGain/TLC5917_test_setCurrentGain.ino
@@ -0,0 +1,71 @@
+//
+//    FILE: TLC5917_test_setCurrentGain.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: test setCurrentGain function.
+//     URL: https://github.com/RobTillaart/TLC5917
+
+
+#include "TLC5917.h"
+
+
+const int DEVICES = 1;
+const int CLOCK = 13;
+const int DATA  = 12;
+const int LE    = 11;
+const int OE    = 10;
+
+TLC5917 tlc(DEVICES, CLOCK, DATA, LE, OE);
+
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("TLC5917_LIB_VERSION: \t");
+  Serial.println(TLC5917_LIB_VERSION);
+  Serial.println();
+
+  if (tlc.begin() == false)
+  {
+    Serial.println("error");
+    while (1);
+  }
+
+  tlc.setSpecialMode();
+  float averageError = 0;
+  float maxError = 0;
+  //  above 2.989 the abs error goes beyond 0.012
+  //  at 3.000 the error is 0.023
+  for (float gain = 0.250; gain <= 2.989; gain += 0.001)
+  {
+    tlc.setCurrentGain(gain);
+    float tmp = tlc.getCurrentGain();
+    float diff = gain - tmp;
+    Serial.print(gain, 3);
+    Serial.print("\t");
+    Serial.print(tmp, 3);
+    Serial.print("\t");
+    Serial.print(diff, 3);
+    Serial.println();
+
+    averageError += diff;
+    if (maxError < abs(diff)) maxError = abs(diff);
+  }
+
+  Serial.println();
+  Serial.print("AVGERR: \t");
+  Serial.println(averageError, 4);
+  Serial.print("MAXERR: \t");
+  Serial.println(maxError, 4);
+
+  tlc.setNormalMode();
+  Serial.println("\ndone...");
+}
+
+
+void loop()
+{
+}
+
+
+//  -- END OF FILE --
diff --git a/libraries/TLC5917/keywords.txt b/libraries/TLC5917/keywords.txt
index 3fe82b57..2710192e 100644
--- a/libraries/TLC5917/keywords.txt
+++ b/libraries/TLC5917/keywords.txt
@@ -20,9 +20,14 @@ enable	KEYWORD2
 disable	KEYWORD2
 isEnabled	KEYWORD2
 
-setCurrentAdjustMode	KEYWORD2
+setSpecialMode	KEYWORD2
 setNormalMode	KEYWORD2
 writeConfiguration	KEYWORD2
+getConfiguration	KEYWORD2
+setGain	KEYWORD2
+setCurrentGain	KEYWORD2
+getVoltageGain	KEYWORD2
+getCurrentGain	KEYWORD2
 
 
 # Instances (KEYWORD2)
@@ -34,3 +39,5 @@ TLC5917_LIB_VERSION	LITERAL1
 TLC5917_OK	LITERAL1
 TLC5917_CHANNEL_ERROR	LITERAL1
 
+TLC5917_NORMAL_MODE	LITERAL1
+TLC5917_SPECIAL_MODE	LITERAL1
diff --git a/libraries/TLC5917/library.json b/libraries/TLC5917/library.json
index b1acf800..61dd6a91 100644
--- a/libraries/TLC5917/library.json
+++ b/libraries/TLC5917/library.json
@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/TLC5917.git"
   },
-  "version": "0.1.1",
+  "version": "0.1.2",
   "license": "MIT",
   "frameworks": "*",
   "platforms": "*",
diff --git a/libraries/TLC5917/library.properties b/libraries/TLC5917/library.properties
index b4f78b1a..490153a9 100644
--- a/libraries/TLC5917/library.properties
+++ b/libraries/TLC5917/library.properties
@@ -1,5 +1,5 @@
 name=TLC5917
-version=0.1.1
+version=0.1.2
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Arduino library for TLC5917 8-Channel Constant-Current LED Sink Drivers.