Chapter 1: Basic Blocks and Functions
Basic Blocks and Functions
Introduction and Overview
This section will outline the most common building blocks of GreenPAKs. Each macrocell type will be given an overview and may include simple techniques and applications for using the block. Further information on specific cells can be found in the particular GreenPAK’s datasheet, or the Help info within the GreenPAK Designer software.
Technique: Learning More About a Macrocell
This technique will work with any version of GreenPAK Designer.
This section provides a brief overview and several techniques for the most common blocks in GreenPAKs. However, it may happen that you wish to learn more about a specific macrocell. This can be done by selecting the macrocell in the GreenPAK Designer, then clicking the Information button (Figure 1) at the bottom-left of the Properties window.
Figure 1 Info Button
Overview: Digital Macrocells
Digital Macrocells are the basic functional components of any GreenPAK. They include:
Common Digital Macrocells:
- Look-Up Tables (LUTs)
- D Flip-Flop (DFF) / Latch
- Counter / Delay (CNT/DLY)
- I2C (many devices)
- SPI (select devices)
- Pattern Generator (PGEN)
- Pipe Delay
- Programmable delay (PDLY)
- Filter / Edge Detector
Many of the components in GreenPAK Designer can be selected to be one of multiple types of macrocells. This is indicated by the name of the digital macrocell: for example, “2-bit LUT0/DFF/LATCH0” can be, as the name implies, a LUT, DFF, or a Latch. The selection of macrocell type is configured using the Type option in the Properties window.
Figure 2 Digital Macrocells
Technique: Configuring Standard Logic w/ LUT Macrocells
This technique will work with any GreenPAK.
Look-up tables can be used in GreenPAK Designer to configure any digital logic for a two, three or four input, single output logic macrocell. The logic configuration can be edited in the Properties window.
Most logic implemented in GreenPAK designs is standardized logic, such as MUX, AND, OR, etc… To expedite these common configurations, the Properties window has a Standard gates option that can automatically convert the logic table into a standard gate configuration. If the Regular shape option is left unchecked the LUT shape will change to the standardized gate symbol.
Figure 3 Config for 3-bit LUT0
GreenPAK ICs contain at least two oscillators; the more recent models, such as the SLG46826, have three oscillators. The most common, non-divided frequencies of the oscillators within GreenPAK are:
- 2KHz low speed, low power oscillator
- 2MHz medium speed
- 25MHz high speed
Each oscillator has several outputs, each with several pre-dividers to allow flexibility in clocking. To save power Auto-power on allows you to turn off the oscillator when the clock is not needed.
More information about oscillators can be found by using the Information button when the component is selected.
Figure 4 Oscillators
Overview: Analog Comparators
Almost every GreenPAK is equipped with two or more analog comparators [ACMPs], each with two input sources; IN+ and IN-. The input source to each can be configured in the Properties window.
More information about analog comparators can be found by using the Information button when the component is selected.
Figure 5 ACMPs
Most I/Os within GreenPAK are very flexible. The I/O capabilities vary significantly from pin to pin and part to part, so a design concept should be mapped to the necessary pin configuration before committing to a specific GreenPAK IC.
Outputs can be configured to be Push-pull or open-drain in either a NMOS or PMOS configuration. A scaling factor, such as 2x, indicates that the output strength is doubled. Additionally, pull-up and pull-down resistor options of 10kΩ, 100kΩ, and 1MΩ are available on output pins.
Multiple input options are available as well, such as: Digital-In, Digital-In with Schmitt trigger, Low Voltage Digital-In and Analog-In. Analog in is used as an input to an ACMP.
Figure 7 Typical I/O Structure
Interconnection with GreenPAK Designer is easy. The system will guide you on which connections you can make. When you click on any connection point, the system:
- Highlights all available connections in green
- Gives you a “rubber band” connection that you can stretch to any of these green connection
- This results in a green wire to show you interconnections you have made
Figure 8 Interconnection