psd511b1 STMicroelectronics, psd511b1 Datasheet - Page 17

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

The PSD5XX
Architecture
14
PSD5XX Family
9.1.1 The DPLD
The DPLD is used for internal address decoding generating the following eight
chip select signals:
The I/O Decoder enabled by the CSIOP generates chip selects for on-chip registers or I/O
ports based on address inputs A[7:0].
As shown in Figure 5, the DPLD consists of a large programmable AND ARRAY. There are
a total of 61 inputs and 8 outputs. Each output consists of a single product term. Although
the user can generate select signals from any of the inputs, the select signals are typically a
function of the address and Page Register inputs. The select signals, which are active High,
are defined by the user in the ABEL file (PSDabel).
The address line inputs to the DPLD include A0, A1 and A8 – A15. If more address lines
are needed, the user can bring in the lines through Port A to the DPLD.
9.1.2 The GPLD
The structure of the General Purpose PLD consists of a programmable AND ARRAY and
3 sets of I/O Macrocells. The ARRAY has 61 input signals, same as the DPLD. From these
inputs, “ANDed” functions are generated as product term inputs to the macrocells. The I/O
Macrocell sets are named after the I/O Ports they are linked to, e.g., the macrocells
connected to Port A are named PA Macrocells. The 3 sets of macrocells, PA, PB and PE,
are similar in structure and function.
Figure 6 shows the output/input path of a GPLD macrocell to the Port pin with which it is
associated. If the Port pin is specified as a GPLD output pin in PSDsoft, the MUX in the I/O
Port Cell selects the GPLD macrocell as an output of the Port pin. The output enable signal
to the buffer in the I/O cell can be controlled by a product term from the AND ARRAY.
If the Port pin is specified as a ZPLD input pin, the MUX in the GPLD macrocell selects the
Port input signal to be one of the 61 signals in the ZPLD Input Bus.
ES0 – ES3
EPROM selects, block 0 to block 3
RS0
SRAM block select
CSIOP
I/O Decoder chip select
PSEL0 – PSEL1
Peripheral I/O mode select signals