C8051F321R Silicon Laboratories Inc, C8051F321R Datasheet - Page 113

• Manufacturer Part Number: C8051F321R
• Description: IC 8051 MCU 16K FLASH 28MLP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F32xr

Specifications of C8051F321R

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 21
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 2.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 13x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Other names: 336-1067-2

12.
The C8051F320/1 devices include 2048 bytes of on-chip XRAM. This XRAM space is split into user RAM
(addresses 0x0000 - 0x03FF) and USB0 FIFO space (addresses 0x0400 - 0x07FF).
12.1. Accessing User XRAM
XRAM can be accessed using the external move instruction (MOVX) and the data pointer (DPTR), or using MOVX
indirect addressing mode. If the MOVX instruction is used with an 8-bit address operand (such as @R1), then the
high byte of the 16-bit address is provided by the External Memory Interface Control Register (EMI0CN as shown in
Figure 12.3). Note: the MOVX instruction is also used for writes to the FLASH memory. See
Memory” on page 107
For any of the addressing modes the upper 5 bits of the 16-bit external data memory address word are "don't cares".
As a result, the 2048-byte RAM is mapped modulo style over the entire 64k external data memory address range. For
example, the XRAM byte at address 0x0000 is also at address 0x0800, 0x1000, 0x1800, 0x2000, etc.
Important Note: The upper 1k of the 2k XRAM functions as USB FIFO space. See
accessing this memory space.
EXTERNAL RAM
for details. The MOVX instruction accesses XRAM by default.
0xFFFF
0x07FF
0x03FF
0x0800
0x0400
0x0000
Figure 12.1. External Ram Memory Map
0x0000 to 0x07FF, wrapped
Same 2048 bytes as from
on 2K-byte boundaries
USB FIFOs
1024 Bytes
1024 Bytes
XRAM
Rev. 1.1
Accessed through USB FIFO
registers
Accessed with the MOVX
instruction
C8051F320/1
Section 12.2
Section “11. FLASH
for details on
113