Panasonic EB-X70 Service Manual

Also see for EBX70 - CELL PHONE: Operating instructions Operating instructions Technical information Service manual

TECHNICAL DESCRIPTIONIssue 1 Section 4 PMCD030901C8Revision 0 – 14 – Service ManualThe Baseband circuits are built around a GSM chipset developed by Texas Instruments. The chipset comprises two chips,CALYPSO+ and SYREN. The highly integrated nature of the chips means that each contain a large number of functions.CALYPSO+ is a signal processing device with a digital signalling processor (DSP) and CPU. The DSP performs channel andspeech encoder/decoder tasks, together with equalisation and encryption. The CPU runs layer 1, 2, and 3 software, controlsthe MMI, SIM and system interfaces, real time clock, and battery and power management. CALYPSO+ also controls SYREN.SYREN provides frame timing, A/D conversion, RF power control, audio interfacing including tone generation, and basebandpower supplies.4.4.2 KeypadThe keyboard interface supports keypads up to 6 columns by 6 rows and has a built-in scanning algorithm for hardware-based key press decoding. Four key press detection modes are offered: matrix, allowing 25 keys to be scanned. When a keybeing pressed, a keypad interrupt is generated. To find which key has been pressed, the software scans each column in turnand reads which row is active. Because of key bounce, the key press is confirmed twice at approximately 20 ms intervals.• Event detection on both key press and key release.• Programmable press detection on key release only.• Long key detection on prolonged key press.• Time out on permanent key press or after keyboard release.Figure 4.6: Keypad ConnectionsThe controller supports detection of single and multiple key presses. On a key press or key release, and allowing fordebounce time, the scanning sequencer is activated. The resulting digital snapshot of the keypad is registered and comparedto the previous one. On change detection, an interrupt is sent to the MCU.10689-1