jueves, 1 de septiembre de 2011

Mods 1.2Ghz 700mw TX from DinoDirect

This transmitter from DinoDirect is of good quality,is declared as transmitter output power 700mW however delivers 850mW in channel 1 to 993 MHz,and  550mW in the channel F to 1280MHz, the design is pretty good, superior to those found on eBay.

The modification in progress is to make it to 20 channels in the ATV, that is from 1220MHz to 1306MHz keeping the same hardware, the microcontroller has no brand, however when connected to an I2C serial memory EEPROM 24C02

Reading unknown uController , the programmer is not recognized as a   PIC16F628 or PIC16F84, though recognized as PIC16C54 or PIC16C74,but not ID chip.

Interface ICSP to unknown uController

The EEPROM I2C 24C02 read from 16F628A as Memory Scanner,the stored data has no relation with the values N PLL chip (either 31.25 or 62.5 or 100KHz step), nor is related to the 7-segment LED display connected to portB,apparently only used to store the last selected channel, and at position 256 EEPROM I2C (last position)

 The uController is code protect enable,the programmer recognized as a   PIC16C84 or PIC16C54, ie, no EEPROM inside uC ,no ID chip, I extracted uC from board, is not possible to rewrite.
I can not seem to do anything for "flashing" this uC. It is Similar to "16C" familly Microchip
I think the only solution is to simply use a PIC with EEPROM inside like the 16F628A or 16F84A in smd package,I will wait until a PIC16F628A SMD.
For Mods the plan is as follows:
1) Use EEPROM 24C02 to store data N PLL,High byte and Low bytes,also the value to load into the PortB  to the Common Anode display 7 seg. ,so cheese can edit how many times you want the frequency in 23cm ATV band(1220-1306MHz)
2) Conect bus I2C to uController 16F628A or similar,same size and compatible pins out.
Partial schematic of uControler, appears PIC16f628  as a matter of simulation with Proteus
this is the I2C EEPROM 24C02 re-written, 20 values each

 Finally got my hands on a microcontroller PIC surface mount, but the first tests were very bad,the small 7-segment LED display could not resist my hot air gun does not work, there are some unlit segments this delayed my project, I decided to use one of my controllers with LCD display to control this Tx

4MHz crystal is used not only for the original controller, but it also is injected into the PLL TSA5520, so I've disconnected the small coupling capacitor in place and a 4MHz crystal and a 18pF capacitor in series