atmega32c1 ATMEL Corporation, atmega32c1 Datasheet - Page 255

• Manufacturer Part Number: atmega32c1
• Description: Atmega32m1 Automotive 8-bit Avr Microcontroller With 32k/64k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

19. ISRC - Current Source
19.1
19.2
19.2.1
7647A–AVR–02/08
Features
Typical applications
LIN Current Source
•
•
The ATmega32/64/M1/C1 features a 100µA ±2% Current Source. After RESET or up on
request, the current is flowing through an external resistor. The voltage can be measured on the
dedicated pin shared with the ADC. Using a resistor in serie with a ≤0.5% tolerance is recom-
mended. To protect the device against big values, the ADC must be configured with AVcc as
internal reference to perform the first measurement. Afterwards, another internal reference can
be chosen according to the previous measured value to refine the result.
When ISRCEN bit is set, the ISRC pin sources 100µA. Otherwise this pin keeps its initial
function.
Figure 19-1. Current Source Block Diagram
During the configuration of a LIN node in a cluster, it may be necessary to attribute dynamically
an unique physical address to every cluster node. The way to do it is not described in the LIN
protocol.
The Current Source offers an excellent solution to associate a physical address to the applica-
tion supported by the LIN node. A full dynamic node configuration can be used to set-up the LIN
nodes in a cluster.
AREF Internal Circuit
100µA Constant current source
± 2% Absolute Accuracy
ADC Input
100 uA
AREFEN
AVCC
ISRCEN
AREF / ISRC
ATmega32/64/M1/C1
External
Resistor
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