Characterization of Single-chip Calculator Circuits - TMS0830 Product Family

The DCM-50A Platform supports the Characterization of TMS0830 Devices in its middle TMS0800 Textool Test Socket with the voltages V_SS set to 9.0V and V_GG set to -3.5V, accordingly.

TMS0833NC

Device-under-Test:

Keyboard: The MBO Expert makes use of a keyboard assembly with 18 individual long-stroke push-button switches arranged in a 9*3 matrix with the rows connected to the D1-D9 Outputs (Display Scan) and the columns connected to the KN, KO and KP Inputs of the TMS0833NC single-chip calculator circuit. The Timeout feature of the TMS0833NC is disabled with a hard-wired connection between DK and KN on the printed circuit board (PCB).

Keyboard Matrix of the MBO Expert:

Display Layout:

The Output Decoder PLA of the TMS0833NC is programmed for 7-Segment displays with the following Output Assignments:

Display Fonts:

The TMS0833NC implements a so-called Timeout feature. When no key presses are detected for about 20 seconds, the display blanks out and shows only a '-' in the leftmost digit to reduce power consumption of the calculator. Timeout is recoverable with an optional [D] key connected between the WDK Output and either the KN or KO Inputs, or pressing any key assigned to the keyboard scan matrix D8, D9/KN, KO, KP. We captured with a Digilent Digital Discovery Logic Analyzer connected to a TMS0833NC and operated in the DCM-50A Platform, the transition between normal operation and Timeout, before returning with pressing the [C] key back to normal operation. The TMS0833NC actually "remembered" the previous content of the display before clearing it due to the [C] key, the optional [D] key would have preserved the previous calculation.

Scanning: Display and keyboard scanning is performed in D9 → D1 direction at a rate of about 370 Hz with the Digits and Segments blanked at State S1 and State S11: