Propeller reset
David Betz
Posts: 14,516
in Propeller 1
What transition resets a Propeller chip? Is it the transition from low to high on the /Reset pin? I'm asking because I'm wondering what would happen if a Propeller is powered up with its /Reset pin held low and then later it is brought high. Would the Propeller come out of reset and start its boot process? Or does that require both the transition from high to low and then low back to high?
Comments
-Phil
Most static CMOS parts have Level Sensitive Reset, which means you can hold RST low during Power Up.
Many MCUs also have a reset width spec, in SysCLKs, - ie they need a CLK active, in order for that Reset to occur.
In those, holding reset low, then raising before the clock starts, gives no reset.
There is also a reset active Icc, that matters in power-wakeup designs, but often is not specified. ie the Icc drawn during a long-term reset.
(In P1 there is also the power drawn, during the long reset-exit)
P1 has an on-chip RC osc as the default driver, so it should meet any SysCLK during reset needs that may be present.
The Propeller datasheet does not specify a minimum hold time for /RST, nor does it specify a maximum glitch length on Vdd before a brownout reset occurs. The latter is probably also a function of the glitch's "depth" and the effects of the chip's internal capacitance.
-Phil