psd511b1 STMicroelectronics, psd511b1 Datasheet - Page 29

• Manufacturer Part Number: psd511b1
• Description: Low Cost Field Programmable Microcontroller Peripherals
• Manufacturer: STMicroelectronics

The PSD5XX
Architecture
(cont.)
26
PSD5XX Family
9.1.3 The PPLD
The Peripheral Programmable Logic Device (PPLD) provides a powerful mechanism for
the user to control the operations of the Counter/Timer and Interrupt Controller. Figure 12 is
the PPLD block diagram. There are six Peripheral Macrocells, four are dedicated to the
Counter/Timer, and two to the Interrupt Controller.
The outputs from the four Peripheral Macrocells, MC2TMR[3:0], are used as
load/store/enable inputs to the Counter/Timer (multiplexed with pin inputs TIMER[3:0] _IN).
The remaining two macrocell outputs (MC2INT[6:7] ), together with two other product terms
(PT2INT4, PT2INT5), can generate up to 4 user defined interrupts to the Interrupt
Controller. The watch-dog output of the Timer (WDOG2PLD) and Interrupt Controller
(INTR2PLD) are available as inputs to the ZPLD’s AND ARRAY.
The structure of a Peripheral Macrocell is shown in Figure 13. The cell has two product term
inputs from the AND ARRAY. The user can select the registered or combinatorial output of
the macrocell, as well as the output polarity. The registers are clocked by the CLKIN clock,
and are cleared by the RESET input during power up.
9.1.4 The ZPLD Power Management
The ZPLD implements a Zero Power Mode, which provides considerable power savings
for low to medium frequency operations. To enable this feature, the ZPLD Turbo bit in the
Power Management Mode Register 0 (PMMR0) has to be turned off.
If none of the 61 inputs to the ZPLD are switching for a time period of 70ns, the ZPLD puts
itself into Zero Power Mode and the current consumption is minimal. The ZPLD will resume
normal operation as soon as one or more of the inputs change state.
Two other features of the ZPLD provide additional power savings:
1. Clock Disable:
2. Product Term Disable:
The ZPLD power configuration is described in the Power Management Unit section.
Users can disable the clock input to the ZPLD and/or macrocells, thereby reducing AC
power consumption.
Unused product terms in the ZPLD are disabled by the PSDsoft Software automatically
for further power savings.