UPD78F9234MC-5A4-A Renesas Electronics America, UPD78F9234MC-5A4-A Datasheet - Page 36

• Manufacturer Part Number: UPD78F9234MC-5A4-A
• Description: MCU 8BIT 8KB FLASH 30PIN
• Manufacturer: Renesas Electronics America
• Series: 78K0S/Kx1+r

Specifications of UPD78F9234MC-5A4-A

• Core Processor: 78K0S
• Core Size: 8-Bit
• Speed: 10MHz
• Connectivity: LIN, UART/USART
• Peripherals: LVD, POR, PWM, WDT
• Number Of I /o: 24
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 5.5 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

34
(3) Stack pointer (SP)
SP
(d) Carry flag (CY)
This is a 16-bit register to hold the start address of the memory stack area. Only the internal high-speed RAM
area can be set as the stack area (the stack area cannot be set except internal high-speed RAM area).
The SP is decremented before writing (saving) to the stack memory and is incremented after reading
(restoring) from the stack memory.
Each stack operation saves/restores data as shown in Figures 3-8 and 3-9.
Cautions 1.
SP15
15
This flag stores overflow and underflow that have occurred upon add/subtract instruction execution. It
stores the shift-out value upon rotate instruction execution and functions as a bit accumulator during bit
operation instruction execution.
SP14
2.
Since generation of reset signal makes the SP contents undefined, be sure to initialize
the SP before using the stack memory.
Stack pointers can be set only to the high-speed RAM area, and only the lower 10 bits
can be actually set.
Thus, if the stack pointer is specified to 0FF00H, it is converted to 0FB00H in the high-
speed RAM area, since 0FF00H is in the SFR area and not in the high-speed RAM area.
When the value is actually pushed onto the stack, 1 is subtracted from 0FB00H to
become 0FAFFH, but since that value is not in the high-speed RAM area, it is converted
to 0FEFFH, which is the same value as when 0FF00H is set to the stack pointer.
SP13 SP12 SP11 SP10 SP9
Figure 3-7. Stack Pointer Configuration
CHAPTER 3 CPU ARCHITECTURE
User’s Manual U17446EJ5V0UD
SP8
SP7
SP6
SP5
SP4
SP3
SP2
SP1
SP0
0