presto_en.pdf - 第79页

Page 79 voltage on pin -MCLR/V PP) or LVP (using th e LVP p in). The LVP programming algorithm can b e disabled in t he device's configuratio n word. Microcont rollers ha ve t he LVP algorit hm enabled from th e pro…

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2 Int.RC 32kHz
SpecSettings.FORTE.ARMCommFreq
integer
Selects communication frequency between FORTE
programmer and the programmed chip. The frequencies
are same as stated in the "Communication frequency"
ComboBox in UP. 0 means the highest frequency, 1 is
lower and so on.
SpecSettings.FORTE.SPI_Flash_Freq
integer
Selects communication frequency between FORTE
programmer and the programmed chip. The frequencies
are same as stated in the "Communication frequency"
ComboBox in UP. 0 means the highest frequency, 1 is
lower and so on.
SpecSettings.FORTE.AVRXTAL.DELAY
integer
represents maximum AVR oscillator frequency
value can be found in *.lng files at item
MainForm.PRESTSpecForm.ComboAVRXTALPresto2.xxx.It
ems where xxx is minimum divisor of system clock of
selected AVR's SPI module. This is 2 for new AVRs, 3 and
4 for older AVRs and 24 for Atmel's 8051 arch.
processors.
This setting can be found in ini file too at
[SpecSettings.FORTE], XTALClk.
SpecSettings.FORTE.AVRXTAL.AutoClk
boolean
If true, faster programming with slow clock is used for
AVR MCUs.
SpecSettings.FORTE.AVRRSTInverse
boolean
If true, the reset signal polarity is assumed to be inverse
in comparison with standard polarity of the reset signal of
the selected chip. It is supported with AVR and 8051
devices.
SpecSettings.FORTE.AVRHVP
boolean
If true, high voltage method is used for AVR MCUs, it is
supported for AVR TPI interface only.
SpecSettings.FORTE.ATxmegaInterface
integer
0 PDI
1 JTAG
SpecSettings.FORTE.i2cSpeed
integer
0 100kHz
1 400kHz
2 1MHz
3 Maximal
SpecSettings.FORTE.i2cAddr
integer
0 first suitable address or N/A
1 second suitable address
etc...
5.13
Appendix B: Use of ICSP
ICSP (In-Circuit Serial Programming) is a method of PIC
microcontroller programming making it possible to
program devices already placed on PCBs.
Two different algorithms may be used for PIC
microcontroller programming: HVP (using programming
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voltage on pin -MCLR/VPP) or LVP (using the LVP pin).
The LVP programming algorithm can be disabled in the
device's configuration word. Microcontrollers have the
LVP algorithm enabled from the production, therefore
their PGM input needs to be treated during the first
programming (PGM input must be in log.0 for the time of
programming by means of the HVP algorithm).
Note: Not all devices have the PGM pin.
5.13.1 Pins Used for
Programming
This chapter describes how to treat pins in the ICSP
programming mode in accordance with the programming
algorithm.
HVP Algorithm
• PGM pin (if the device has one) must be maintained in
log.0!!
• -MCLR/VPP must be separated from the resetting
circuits (with a 10kΩ resistor, for example).
Aprogramming voltage is supplied to this pin P(VPP)
for programming. The leading edge and the voltage
level at VPP must not be influenced by the application.
The PRESTO programmer supports only fixed voltage
of 13V on pin P(VPP) in contrast to adjustable voltage
within a range of 6.5V to 17V supported by FORTE.
Please check limit voltage value on pin -MCLR/VPP of
the PIC device to be programmed by PRESTO.
• RB6 and RB7 pins must not be influenced by the
application during programming.
LVP algorithm (without VPP)
• RB6, RB7, PGM and -MCLR/VPP pins must not be
influenced by the application during programming. All
pins are in various logical levels during programming.
Loading of Different
Programmer Pins
The maximum current drawn from I/O pins, from pins
P(VPP) and VDD can be found in the Technical
Specification.
OTP (One-Time Programmable) devices have a
considerably higher current consumption on pin P(VPP)
than devices with a FLASH memory. Therefore the
application should not have any additional current
consumption at pin P(VPP) in case of OTP.
Data pins may have their signals changing at a speed of
several MHz, so the application must not influence the
signals in any significant way.
5.13.2 Power Supply Options
Connecting the shared data and power supply ground
(GND) is obviously necessary for all cases. The
microcontroller being programmed can be fed:
• externally from an application
• internally from a programmer
The external power supply from the application cannot be
used for some types of microcontroller having the -MCLR/
VPP pin alternatively configurable as an I/O.
The internal power supply can be used only in cases
where the application does not draw too much current
from programmer's feeding pin (VDD). The maximum
allowed current consumption can be found in the
Technical Specification.
Both PRESTO and FORTE programmers feature an
overcurrent protection. PRESTO has a software protection
in which an output gets disconnected by the running UP
program having detected an overload. FORTE has a
hardware protection, which does not depend on the
control software.
The programmer switches the power supply off if the
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maximum load is substantially exceeded for a certain
time (this time is adjustable). PRESTO checks for the
overload state the whole time the power supply is
connected.
Support for an external power supply is integrated in both
PRESTO and FORTE hardware. The programmer feeds the
input and output circuits with a voltage connected to pin
VDD. The voltage may be lower than 5V.
Advice
When designing the process, please pay special attention
to the type of device to be programmed – if it can be not
only operated but also programmed at a voltage lower
than 5V.
Power Supply Capacities in
Application
If there are capacities present at the application's power-
supply pin that would slow down the power on/off
switching and application is fed from programmer during
programming, longer charging/discharging times need to
be set in UP. In other case UP will probably announce
overcurrent on VDD pin.
An approximate time that should be set in the program:
t[μs] = 2.5 × C[μF] × R[Ω].
The equivalent resistance is presented in table following
table:
Programmer
Charging current
Discharging current
PRESTO
Corresponds to 50Ω
Corresponds to 1kΩ
FORTE
Corresponds to 50Ω
Corresponds to 27Ω
Table10: Equivalent resistance of pin VDD
Example
The necessary charging time for an application with
a33μF capacitor programmed with PRESTO:
2.5×33×50=4125μs
discharging:
2.5×33×1000=82.5ms.
For further information on the setting see
▸ Delay for VDD
switching on/off when supplied from programmer.