Wrong ENABLE polarization for DRV8825
1sm1rk opened this issue · comments
Same as #51 for the DRV8825. To enable the driver the enable pin must be pulled up (HIGH) and to disable the driver the enable pin must be pulled down (LOW)
That's not true. The DRV8825 datasheet clearly states that ENABLE must be pulled DOWN to enable the driver.
From http://www.ti.com/lit/ds/symlink/drv8825.pdf:
nENBL: Logic high to disable device outputs and indexer operation, logic low to enable. Internal pulldown.
These default RESET and SLEEP states are ones that prevent the driver from operating; both of these pins must be high to enable the driver https://www.pololu.com/product/2133
LOW -> DISABLE
HIGH -> ENABLE
with your library enable() disables my stepper, disable() - enables..
How to fix it? should I change stepper pins ?
The enable function was meant for the ENABLE pin on the carrier board, so from that perspective it works correctly, sending a logic LOW to enable. SLEEP would be hardwired to HIGH in this model *).
The Pololu minimal wiring suggests controling via SLEEP instead and logic HIGH to enable, which causes this issue and it's a problem specific to this particular board. Since a lot of people will wire it based on the example, I think we may need a way to select one or the other instead.
*) The reason for using ENABLE is because while SLEEP does reduce consumption to a super low 10µA, it also resets the internal position counter and needs >1ms time to wake up and be able to read STEP inputs.
The few mA that the driver uses in disabled state are similar to MCU usage and maybe dwarfed by the first few milliseconds of stepper motion anyway.
Closing this, rolling into #75