TS80C51RA2-VCB Atmel, TS80C51RA2-VCB Datasheet - Page 16

• Manufacturer Part Number: TS80C51RA2-VCB
• Description: IC MCU 8BIT 256BYTE 40MHZ 44PLCC
• Manufacturer: Atmel
• Series: 80Cr

Specifications of TS80C51RA2-VCB

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 40/30MHz
• Connectivity: UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Type: ROMless
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 44-PLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -

TS80C51RA2/RD2
TS83C51RB2/RC2/RD2
TS87C51RB2/RC2/RD2
6.3. Expanded RAM (XRAM)
The TS80C51Rx2 provide additional Bytes of ramdom access memory (RAM) space for increased data
parameter handling and high level language usage.
RA2, RB2 and RC2 devices have 256 bytes of expanded RAM, from 00H to FFH in external data space;
RD2 devices have 768 bytes of expanded RAM, from 00H to 2FFH in external data space.
The TS80C51Rx2 has internal data memory that is mapped into four separate segments.
The four segments are:
The Lower 128 bytes can be accessed by either direct or indirect addressing. The Upper 128 bytes can be
accessed by indirect addressing only. The Upper 128 bytes occupy the same address space as the SFR. That
means they have the same address, but are physically separate from SFR space.
When an instruction accesses an internal location above address 7FH, the CPU knows whether the access is
to the upper 128 bytes of data RAM or to SFR space by the addressing mode used in the instruction.
The stack pointer (SP) may be located anywhere in the 256 bytes RAM (lower and upper RAM) internal
data memory. The stack may not be located in the XRAM.
16
• 1. The Lower 128 bytes of RAM (addresses 00H to 7FH) are directly and indirectly addressable.
• 2. The Upper 128 bytes of RAM (addresses 80H to FFH) are indirectly addressable only.
• 3. The Special Function Registers, SFRs, (addresses 80H to FFH) are directly addressable only.
• 4. The expanded RAM bytes are indirectly accessed by MOVX instructions, and with the EXTRAM
Instructions that use direct addressing access SFR space. For example: MOV 0A0H, # data ,accesses the SFR
at location 0A0H (which is P2).
Instructions that use indirect addressing access the Upper 128 bytes of data RAM. For example: MOV @R0,
# data where R0 contains 0A0H, accesses the data byte at address 0A0H, rather than P2 (whose address is 0A0H).
The 256 or 768 XRAM bytes can be accessed by indirect addressing, with EXTRAM bit cleared and MOVX
instructions. This part of memory which is physically located on-chip, logically occupies the first 256 or 768
bytes of external data memory.
With EXTRAM = 0, the XRAM is indirectly addressed, using the MOVX instruction in combination with any
of the registers R0, R1 of the selected bank or DPTR. An access to XRAM will not affect ports P0, P2, P3.6
(WR) and P3.7 (RD). For example, with EXTRAM = 0, MOVX @R0, # data where R0 contains 0A0H,
accesses the XRAM at address 0A0H rather than external memory. An access to external data memory locations
higher than FFH (i.e. 0100H to FFFFH) (higher than 2FFH (i.e. 0300H to FFFFH for RD devices) will be
performed with the MOVX DPTR instructions in the same way as in the standard 80C51, so with P0 and P2
as data/address busses, and P3.6 and P3.7 as write and read timing signals. Refer to Figure . For RD devices,
accesses to expanded RAM from 100H to 2FFH can only be done thanks to the use of DPTR.
With EXTRAM = 1, MOVX @Ri and MOVX @DPTR will be similar to the standard 80C51. MOVX @ Ri
will provide an eight-bit address multiplexed with data on Port0 and any output port pins can be used to output
higher order address bits. This is to provide the external paging capability. MOVX @DPTR will generate a
sixteen-bit address. Port2 outputs the high-order eight address bits (the contents of DPH) while Port0 multiplexes
the low-order eight address bits (DPL) with data. MOVX @ Ri and MOVX @DPTR will generate either read
or write signals on P3.6 (WR) and P3.7 (RD).
bit cleared in the AUXR register. (See Table 5.)
Rev. C - 06 March, 2001