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S2 position | Default position | Effect on 1.2 V and 2.5 V rails |
|---|---|---|
FX2 PON (on) |  | 1.2 V and 2.5 V rails controlled by USB FX2 microcontroller (signal FX2_PS_EN) PS_EN = FX2_PS_EN = high or low |
PON (off) |  | 1.2 V and 2.5 V rails always enabled (PS_EN = high) PS_EN ≠ FX_PS_EN |
Table 14: Slide switch S2 settings overview (1.2 V and 2.5 V rails only).
Signal FX2_PS_EN
To command signal FX2_PS_EN, read the reference firmware code.
IOD = 0x03; // Enable PS_EN and disable PROG_B
OED = 0x03; // Configure PS_EN and PROG as outputs
| Port D Pin | Alternate Function | Alternate Function is Selected By... | Alternate Function is Described in... |
|---|---|---|---|
| PD.7:0 | FD[15:8] | IFCFG1 = 1 and any WORDWIIDE bit = 1 Chapter 9 of fx2_trm.pdf | Slave FIFOs chapter 9 on page 99 |
Table from EZ-USB(R) Technical Reference Manual (EZ-USB_TRM.pdf).
Slide Switch S2 = FX2 PON
When slide switch S2 is in the left position ( = FX2 PON : power rails conditionally on depending on signal FX2_PS_EN), signal PS_EN is set to signal FX2_PS_EN (PS_EN = FX2_PS_EN) driven by the EZ-USB FX2LP USB FX2 microcontroller under user control (IOD and OED of fw.c).
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