Rainbow Electronics AT89LP214 - Manual (Page 65)

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3538A–MICRO–7/06
AT89LP213/214 [Preliminary]
23. Programming the Flash Memory
The Atmel AT89LP213/214 microcontroller features 2KB of on-chip In-System Programmable
Flash program memory. In-System Programming (ISP) allows programming and reprogramming
of the microcontroller positioned inside the end system. Using a simple 4-wire SPI interface, the
In-System programmer communicates serially with the AT89LP213/214 microcontroller, repro-
gramming all nonvolatile memories on the chip. In-System programming eliminates the need for
physical removal of the chips from the system. This will save time and money, both during devel-
opment in the lab, and when updating the software or parameters in the field. The ISP interface
of the AT89LP213/214 includes the following features:
• Four Wire SPI Programming Interface
• Active-low Reset Entry into Programming
• Slave Select allows multiple devices on same interface
• User Signature Array
• Flexible Page Programming
• Row Erase Capability
• Page Write with Auto-Erase Commands
• Programming Status Register
For more detailed information on In-System Programming, refer to the Application Note entitled
“AT89LP In-System Programming Specification”.
23.1 Physical Interface
In-System Programming utilizes the Serial Peripheral Interface (SPI) pins of an AT89LP213/214
microcontroller. The SPI is a full duplex synchronous serial interface consisting of four wires:
Serial Clock (SCK), Master-In/Slave-out (MISO), Master-out/Slave-in (MOSI), and an active-low
Slave Select (SS). When programming an AT89LP213/214 device, the programmer always
operates as the SPI master, and the target system always operates as the SPI slave. To enter or
remain in In-System Programming mode the device’s reset line (RST) must be held active (low).
With the addition of VCC and GND, an AT89LP213/214 microcontroller can be programmed with
a minimum of seven connections as shown in
Figure 23-1 .
Figure 23-1. In-System Programming Device Connections
AT89LP213/214
VCC
P1.3/RST
P1.7/SCK
P1.5/MOSI
GND
Serial Clock
Serial In
RST
P1.4/SS
P1.6/MISO Serial Out
SS