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allow SPI display usage without CS pin #376

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Merged
merged 2 commits into from
Dec 28, 2022
Merged

allow SPI display usage without CS pin #376

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e6b81a2
allow SPI display usage without CS pin
seife Nov 29, 2022
54dc9b4
Add curly braces
marcelstoer Dec 28, 2022
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4 changes: 3 additions & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -125,9 +125,11 @@ or for the SH1106:
#include <SPI.h>
#include "SH1106Spi.h"

SH1106Spi display(D0, D2); // RES, DC
SH1106Spi display(D0, D2, CS); // RES, DC, CS
```

In case the CS pin is not used (hard wired to ground), pass CS as -1.

## API

### Display Control
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28 changes: 18 additions & 10 deletions src/SH1106Spi.h
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@ class SH1106Spi : public OLEDDisplay {
uint8_t _cs;

public:
/* pass _cs as -1 to indicate "do not use CS pin", for cases where it is hard wired low */
SH1106Spi(uint8_t _rst, uint8_t _dc, uint8_t _cs, OLEDDISPLAY_GEOMETRY g = GEOMETRY_128_64) {
setGeometry(g);

Expand All @@ -51,7 +52,9 @@ class SH1106Spi : public OLEDDisplay {

bool connect(){
pinMode(_dc, OUTPUT);
pinMode(_cs, OUTPUT);
if (_cs != (uint8_t) -1) {
pinMode(_cs, OUTPUT);
}
pinMode(_rst, OUTPUT);

SPI.begin ();
Expand Down Expand Up @@ -105,27 +108,27 @@ class SH1106Spi : public OLEDDisplay {
sendCommand(0xB0 + y);
sendCommand(minBoundXp2H);
sendCommand(minBoundXp2L);
digitalWrite(_cs, HIGH);
set_CS(HIGH);
digitalWrite(_dc, HIGH); // data mode
digitalWrite(_cs, LOW);
set_CS(LOW);
for (x = minBoundX; x <= maxBoundX; x++) {
SPI.transfer(buffer[x + y * displayWidth]);
}
digitalWrite(_cs, HIGH);
set_CS(HIGH);
yield();
}
#else
for (uint8_t y=0; y<displayHeight/8; y++) {
sendCommand(0xB0 + y);
sendCommand(0x02);
sendCommand(0x10);
digitalWrite(_cs, HIGH);
set_CS(HIGH);
digitalWrite(_dc, HIGH); // data mode
digitalWrite(_cs, LOW);
set_CS(LOW);
for( uint8_t x=0; x < displayWidth; x++) {
SPI.transfer(buffer[x + y * displayWidth]);
}
digitalWrite(_cs, HIGH);
set_CS(HIGH);
yield();
}
#endif
Expand All @@ -135,12 +138,17 @@ class SH1106Spi : public OLEDDisplay {
int getBufferOffset(void) {
return 0;
}
inline void set_CS(bool level) {
if (_cs != (uint8_t) -1) {
digitalWrite(_cs, level);
}
};
inline void sendCommand(uint8_t com) __attribute__((always_inline)){
digitalWrite(_cs, HIGH);
set_CS(HIGH);
digitalWrite(_dc, LOW);
digitalWrite(_cs, LOW);
set_CS(LOW);
SPI.transfer(com);
digitalWrite(_cs, HIGH);
set_CS(HIGH);
}
};

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28 changes: 18 additions & 10 deletions src/SSD1306Spi.h
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@ class SSD1306Spi : public OLEDDisplay {
uint8_t _cs;

public:
/* pass _cs as -1 to indicate "do not use CS pin", for cases where it is hard wired low */
SSD1306Spi(uint8_t _rst, uint8_t _dc, uint8_t _cs, OLEDDISPLAY_GEOMETRY g = GEOMETRY_128_64) {
setGeometry(g);

Expand All @@ -57,7 +58,9 @@ class SSD1306Spi : public OLEDDisplay {

bool connect(){
pinMode(_dc, OUTPUT);
pinMode(_cs, OUTPUT);
if (_cs != (uint8_t) -1) {
pinMode(_cs, OUTPUT);
}
pinMode(_rst, OUTPUT);

SPI.begin ();
Expand Down Expand Up @@ -111,16 +114,16 @@ class SSD1306Spi : public OLEDDisplay {
sendCommand(minBoundY);
sendCommand(maxBoundY);

digitalWrite(_cs, HIGH);
set_CS(HIGH);
digitalWrite(_dc, HIGH); // data mode
digitalWrite(_cs, LOW);
set_CS(LOW);
for (y = minBoundY; y <= maxBoundY; y++) {
for (x = minBoundX; x <= maxBoundX; x++) {
SPI.transfer(buffer[x + y * displayWidth]);
}
yield();
}
digitalWrite(_cs, HIGH);
set_CS(HIGH);
#else
// No double buffering
sendCommand(COLUMNADDR);
Expand All @@ -136,27 +139,32 @@ class SSD1306Spi : public OLEDDisplay {
sendCommand(0x3);
}

digitalWrite(_cs, HIGH);
set_CS(HIGH);
digitalWrite(_dc, HIGH); // data mode
digitalWrite(_cs, LOW);
set_CS(LOW);
for (uint16_t i=0; i<displayBufferSize; i++) {
SPI.transfer(buffer[i]);
yield();
}
digitalWrite(_cs, HIGH);
set_CS(HIGH);
#endif
}

private:
int getBufferOffset(void) {
return 0;
}
inline void set_CS(bool level) {
if (_cs != (uint8_t) -1) {
digitalWrite(_cs, level);
}
};
inline void sendCommand(uint8_t com) __attribute__((always_inline)){
digitalWrite(_cs, HIGH);
set_CS(HIGH);
digitalWrite(_dc, LOW);
digitalWrite(_cs, LOW);
set_CS(LOW);
SPI.transfer(com);
digitalWrite(_cs, HIGH);
set_CS(HIGH);
}
};

Expand Down