KEYPADA_W - Pin Description
Frozen Content
The following pin description is for the KEYPADA_W when used on the schematic. In an OpenBus System, although the same signals are present, the abstract nature of the system hides the pin-level Wishbone interfaces. The external interface signals to the keypad will be made available as sheet entries, associated with the parent sheet symbol used to reference the underlying OpenBus System.
Table 1. KEYPADA_W Pin description.| Name | Type | Polarity / Bus size | Description |
|---|---|---|---|
| Control Signals | |||
| CLK_I | I | Rise | External system clock |
| CLK_1MHZ | I | Rise | External clock signal. This signal must be 1 MHz in frequency. Clock dividers must be used within the design to achieve this frequency. The initial (undivided) signal can be sourced either from the system (NanoBoard) clock or some other reference clock in the design |
| RST_I | I | High | External system reset |
| Host Processor Interface Signals | |||
| STB_I | I | High | Strobe signal. When asserted, indicates the start of a valid Wishbone data transfer cycle |
| CYC_I | I | High | Cycle signal. When asserted, indicates the start of a valid Wishbone cycle |
| ACK_O | O | High | Standard Wishbone device acknowledgement signal. When this signal goes high, the Controller (Wishbone Slave) has finished execution of the requested action and the current bus cycle is terminated |
| ADR_I | I | Level | Standard Wishbone address bus, used to select an internal register of the slave device for writing to/reading from. 0 = KEYREG 1 = VALKEYREG |
| DAT_O | O | 8 | Data to be sent to host microcontroller |
| WE_I | I | Level | Write enable signal. Used to indicate whether the current local bus cycle is a Read or Write cycle: 0 = Read 1 = Write |
| INT_O | O | High | Interrupt output. This output is connected straight from the VALKEY register. When a key has been detected as being validly pressed on the keypad, the output of this register will be High |
| Keypad Interface Signals | |||
| COL | I | 4 | Value returned by keypad matrix |
| ROW | O | 4 | Driving output to the keypad matrix |