ManuelW/grbl-LPC-CoreXY
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Merge pull request #289 from Travis-Snoozy/master

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Add support for active-high limit switches
This commit is contained in:
Sonny Jeon 2013-11-23 14:04:36 -08:00
commit cc3212d54a
2 changed files with 16 additions and 1 deletions
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6
config.h
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@ -171,6 +171,12 @@
// successful values for certain setups have ranged from 10 to 20us. // successful values for certain setups have ranged from 10 to 20us.
// #define STEP_PULSE_DELAY 10 // Step pulse delay in microseconds. Default disabled. // #define STEP_PULSE_DELAY 10 // Step pulse delay in microseconds. Default disabled.
// Uncomment the following define if you are using hardware that drives high when your limits
// are reached. You will need to ensure that you have appropriate pull-down resistors on the
// limit switch input pins, or that your hardware drives the pins low when they are open (non-
// triggered).
// #define LIMIT_SWITCHES_ACTIVE_HIGH
// --------------------------------------------------------------------------------------- // ---------------------------------------------------------------------------------------
// TODO: Install compile-time option to send numeric status codes rather than strings. // TODO: Install compile-time option to send numeric status codes rather than strings.

11
limits.c
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@ -38,7 +38,11 @@
void limits_init() void limits_init()
{ {
LIMIT_DDR &= ~(LIMIT_MASK); // Set as input pins LIMIT_DDR &= ~(LIMIT_MASK); // Set as input pins
LIMIT_PORT |= (LIMIT_MASK); // Enable internal pull-up resistors. Normal high operation. #ifndef LIMIT_SWITCHES_ACTIVE_HIGH
LIMIT_PORT |= (LIMIT_MASK); // Enable internal pull-up resistors. Normal high operation.
#else // LIMIT_SWITCHES_ACTIVE_HIGH
LIMIT_PORT &= ~(LIMIT_MASK); // Normal low operation. Requires external pull-down.
#endif // !LIMIT_SWITCHES_ACTIVE_HIGH
if (bit_istrue(settings.flags,BITFLAG_HARD_LIMIT_ENABLE)) { if (bit_istrue(settings.flags,BITFLAG_HARD_LIMIT_ENABLE)) {
LIMIT_PCMSK |= LIMIT_MASK; // Enable specific pins of the Pin Change Interrupt LIMIT_PCMSK |= LIMIT_MASK; // Enable specific pins of the Pin Change Interrupt
PCICR |= (1 << LIMIT_INT); // Enable Pin Change Interrupt PCICR |= (1 << LIMIT_INT); // Enable Pin Change Interrupt
@ -89,6 +93,11 @@ ISR(LIMIT_INT_vect)
// NOTE: Only the abort runtime command can interrupt this process. // NOTE: Only the abort runtime command can interrupt this process.
static void homing_cycle(uint8_t cycle_mask, int8_t pos_dir, bool invert_pin, float homing_rate) static void homing_cycle(uint8_t cycle_mask, int8_t pos_dir, bool invert_pin, float homing_rate)
{ {
#ifdef LIMIT_SWITCHES_ACTIVE_HIGH
// When in an active-high switch configuration, invert_pin needs to be adjusted.
invert_pin = !invert_pin;
#endif
// Determine governing axes with finest step resolution per distance for the Bresenham // Determine governing axes with finest step resolution per distance for the Bresenham
// algorithm. This solves the issue when homing multiple axes that have different // algorithm. This solves the issue when homing multiple axes that have different
// resolutions without exceeding system acceleration setting. It doesn't have to be // resolutions without exceeding system acceleration setting. It doesn't have to be