Allow obscure-but-needed case of no TFT chip select (-1)

Author: PaintYourDragon

Adafruit_SPITFT.cpp

@@ -87,21 +87,30 @@ Adafruit_SPITFT::Adafruit_SPITFT(uint16_t w, uint16_t h,
     _miso = miso;
     _freq = 0;
 #ifdef USE_FAST_PINIO
-    csport      = (RwReg *)portOutputRegister(digitalPinToPort(_cs));
-    cspinmask   = digitalPinToBitMask(_cs);
-    dcport      = (RwReg *)portOutputRegister(digitalPinToPort(_dc));
-    dcpinmask   = digitalPinToBitMask(_dc);
-    clkport     = (RwReg *)portOutputRegister(digitalPinToPort(_sclk));
-    clkpinmask  = digitalPinToBitMask(_sclk);
-    mosiport    = (RwReg *)portOutputRegister(digitalPinToPort(_mosi));
-    mosipinmask = digitalPinToBitMask(_mosi);
+    dcport      = (RwReg *)portOutputRegister(digitalPinToPort(dc));
+    dcpinmask   = digitalPinToBitMask(dc);
+    clkport     = (RwReg *)portOutputRegister(digitalPinToPort(sclk));
+    clkpinmask  = digitalPinToBitMask(sclk);
+    mosiport    = (RwReg *)portOutputRegister(digitalPinToPort(mosi));
+    mosipinmask = digitalPinToBitMask(mosi);
     if(miso >= 0){
-        misoport    = (RwReg *)portInputRegister(digitalPinToPort(_miso));
-        misopinmask = digitalPinToBitMask(_miso);
+        misoport    = (RwReg *)portInputRegister(digitalPinToPort(miso));
+        misopinmask = digitalPinToBitMask(miso);
     } else {
         misoport    = 0;
         misopinmask = 0;
     }
+    if(cs >= 0) {
+        csport    = (RwReg *)portOutputRegister(digitalPinToPort(cs));
+        cspinmask = digitalPinToBitMask(cs);
+    } else {
+        // No chip-select line defined; might be permanently tied to GND.
+        // Assign a valid GPIO register (though not used for CS), and an
+        // empty pin bitmask...the nonsense bit-twiddling might be faster
+        // than checking _cs and possibly branching.
+        csport    = dcport;
+        cspinmask = 0;
+    }
 #endif
 }
 
@@ -126,16 +135,22 @@ Adafruit_SPITFT::Adafruit_SPITFT(uint16_t w, uint16_t h,
     _miso = -1;
     _freq = 0;
 #ifdef USE_FAST_PINIO
-    csport      = (RwReg *)portOutputRegister(digitalPinToPort(_cs));
-    cspinmask   = digitalPinToBitMask(_cs);
-    dcport      = (RwReg *)portOutputRegister(digitalPinToPort(_dc));
-    dcpinmask   = digitalPinToBitMask(_dc);
     clkport     = 0;
     clkpinmask  = 0;
     mosiport    = 0;
     mosipinmask = 0;
     misoport    = 0;
     misopinmask = 0;
+    dcport      = (RwReg *)portOutputRegister(digitalPinToPort(dc));
+    dcpinmask   = digitalPinToBitMask(dc);
+    if(cs >= 0) {
+        csport    = (RwReg *)portOutputRegister(digitalPinToPort(cs));
+        cspinmask = digitalPinToBitMask(cs);
+    } else {
+        // See notes in prior constructor.
+        csport    = dcport;
+        cspinmask = 0;
+    }
 #endif
 }
 
@@ -150,10 +165,12 @@ void Adafruit_SPITFT::initSPI(uint32_t freq)
     _freq = freq;
 
     // Control Pins
+    if(_cs >= 0) {
+        pinMode(_cs, OUTPUT);
+        digitalWrite(_cs, HIGH); // Deselect
+    }
     pinMode(_dc, OUTPUT);
     digitalWrite(_dc, LOW);
-    pinMode(_cs, OUTPUT);
-    digitalWrite(_cs, HIGH);
 
     // Software SPI
     if(_sclk >= 0){

Adafruit_SPITFT_Macros.h

@@ -8,13 +8,13 @@
 #ifdef USE_FAST_PINIO
 #define SPI_DC_HIGH()           *dcport |=  dcpinmask
 #define SPI_DC_LOW()            *dcport &= ~dcpinmask
-#define SPI_CS_HIGH()           *csport |= cspinmask
+#define SPI_CS_HIGH()           *csport |=  cspinmask
 #define SPI_CS_LOW()            *csport &= ~cspinmask
 #else
 #define SPI_DC_HIGH()           digitalWrite(_dc, HIGH)
 #define SPI_DC_LOW()            digitalWrite(_dc, LOW)
-#define SPI_CS_HIGH()           digitalWrite(_cs, HIGH)
-#define SPI_CS_LOW()            digitalWrite(_cs, LOW)
+#define SPI_CS_HIGH()           { if(_cs >= 0) digitalWrite(_cs, HIGH) }
+#define SPI_CS_LOW()            { if(_cs >= 0) digitalWrite(_cs, LOW)  }
 #endif
 
 /*
@@ -24,8 +24,8 @@
 #ifdef USE_FAST_PINIO
 #define SSPI_MOSI_HIGH()        *mosiport |=  mosipinmask
 #define SSPI_MOSI_LOW()         *mosiport &= ~mosipinmask
-#define SSPI_SCK_HIGH()         *clkport |=  clkpinmask
-#define SSPI_SCK_LOW()          *clkport &= ~clkpinmask
+#define SSPI_SCK_HIGH()         *clkport  |=  clkpinmask
+#define SSPI_SCK_LOW()          *clkport  &= ~clkpinmask
 #define SSPI_MISO_READ()        ((*misoport & misopinmask) != 0)
 #else
 #define SSPI_MOSI_HIGH()        digitalWrite(_mosi, HIGH)

library.properties

@@ -1,5 +1,5 @@
 name=Adafruit GFX Library
-version=1.2.6
+version=1.2.7
 author=Adafruit
 maintainer=Adafruit <[email protected]>
 sentence=Adafruit GFX graphics core library, this is the 'core' class that all our other graphics libraries derive from.