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reverse SS HIGH/LOW in Scanner_ShiftRegsPISOMultiRow::scan()

tags/v0.6.3
wolfv6 7 years ago
parent
3fa0aee2e2
commit
d9465be221
3 changed files with 21 additions and 8 deletions
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  1. 1
    0
      doc/keybrd_library_user_guide.md
  2. 19
    7
      src/Scanner_ShiftRegsPISOMultiRow.cpp
  3. 1
    1
      src/Scanner_ShiftRegsPISOSingleRow.cpp

+ 1
- 0
doc/keybrd_library_user_guide.md View File

@@ -142,6 +142,7 @@ The following is a listing of items to check when a new keybrd sketch or keyboar
Development-environment items to check:
* If the keyboard has an I/O expander, power cycle (replug the USB) after loading the HEX file.
* Sometimes sketch will not loading properly if two instances of Arduino IDE are open.
* For compile error:
```
'KEY_A' was not declared in this scope

+ 19
- 7
src/Scanner_ShiftRegsPISOMultiRow.cpp View File

@@ -21,32 +21,44 @@ Initializes shift register's shift/load pin.
*/
void Scanner_ShiftRegsPISOMultiRow::begin()
{
digitalWrite(slaveSelect, HIGH); //initialize ??only needed for first scan
SPI.begin(); //todo move this to constructor or init()
}

/* scan() strobes the row's strobePin and returns state of the shift register's input pins.
strobePin is Arduino pin number connected to this row.
Bit patterns are 1 bit per key.

Scanner_ShiftRegsPISOMultiRow class was tested on two sets of 74HC165 shift registers
and 74AHC1G126 tri-state buffer chips

74HC165 is not an SPI device.
The 74HC165 SH/LD polarity is the inverse of SPI slave-select convention.
Most SPI chips will high-Z their MISO pin when their slave select signal is high.
To use SPI-like protocol, 74HC*126 will high-Z the MISO pin when the slave select signal is low.

SPI.beginTransaction() and SPI.endTransaction() are not needed,
but would be needed if trackball uses interrupts.
*/
read_pins_t Scanner_ShiftRegsPISOMultiRow::scan(const uint8_t strobePin)
{
read_pins_t readState = 0; //bits, 1 means key is pressed, 0 means released

SPI.beginTransaction( SPISettings(5000000, MSBFIRST, SPI_MODE0) ); //control SPI bus, 5 MHz
digitalWrite(strobePin, strobeOn); //strobe on

digitalWrite(slaveSelect, LOW); //load parallel inputs to registers
//SPI.beginTransaction( SPISettings(5000000, MSBFIRST, SPI_MODE0) ); //control SPI bus, 5 MHz

digitalWrite(strobePin, strobeOn); //strobe on
delayMicroseconds(20); //photo-transistor at 3.3v needs 20 ms to stablize

delayMicroseconds(3); //time to stabilize photo-transistor todo need?
delayMicroseconds(50); //todo for sr2_LEDs_strobe.ino
digitalWrite(slaveSelect, HIGH); //shift the data toward a serial output
digitalWrite(slaveSelect, HIGH); //shift the data toward a serial output

digitalWrite(strobePin, strobeOff); //strobe off

SPI.transfer(&readState, byte_count);

SPI.endTransaction();
//SPI.endTransaction();

digitalWrite(slaveSelect, LOW); //load parallel inputs to registers

return readState;
}

+ 1
- 1
src/Scanner_ShiftRegsPISOSingleRow.cpp View File

@@ -36,9 +36,9 @@ read_pins_t Scanner_ShiftRegsPISOSingleRow::scan(const uint8_t strobePin)
read_pins_t readState = 0; //bits, 1 means key is pressed, 0 means released

//read all the column pins
digitalWrite(slaveSelect, LOW); //load parallel inputs to the register
digitalWrite(slaveSelect, HIGH); //shift the data toward a serial output
SPI.transfer(&readState, byte_count);
digitalWrite(slaveSelect, LOW); //load parallel inputs to the register

return readState;
}