25-04-2019, 10:08 PM
Hedghog II
Hedghog II is mainly in response to all the recent trouble with the EP2C5 FPGA boards. For the most part it is the Same as Hedghog but with a few changes.
What's new in Hedghog II?
The biggest difference is the FPGA board is dispensed with. Now all the components are mounted on a single PCB.
The FPGA is changed to a more modern EP4CE6E22C8N.
The R2R DAC is changed from 9 bit to 10 bit.
It now can be used in modulator only mode.
The video out socked is moved to the rear panel and an extra toggle switch is added to the front panel.
The DIP switch is now a 6 pole type.
It has a test mode that drives the Test card from the 50 MHz clock. This will allow the 405 side of the FPGA to be tested without the video clock been required and so should help to identify video decoder problems.
There are some circuit changes.
A 50 MHz oscillator feeds the FPGA. From this the FPGA then generates all the other clocks. This includes a 14.31818 MHz clock for the video decoder which previously required it's own 14.31818 MHz crystal.
The pull-up resistors for the switches have been removed and it now uses the weak pull-up's provided by the FPGA.
The unused section of the video amplifier chip is now used together with a analogue switch to enable it to be used in modulator only mode.
To provide all the required power rails there are now 5 voltage regulators 5V, 3.3V, 2.5V, 1.8V and 1.2V.
It still fits on a double sided PCB of the same dimensions as the Hedghog PCB and so will fit the same cases.
Even though the EP4CE6E is a more modern FPGA with more resources on it that the EP2C5, it cost less.
The FPGA flash memory recommended for use with the EP4CE6E is the EPCS16SI8N. I have used the IS25LP016D-JNLE-TR which is pin for pin compatible and is a fraction of the cost.
The FPGA might look intermediating to solder but the pin pitch is the same as the video decoder. So if you are able to solder the video decoder there is no reason why you cant solder the FPGA, it just takes a little longer. In fact the I find FPGA easier to position because it is larger and because of it's size it is easy to place tape across it to hold it in place while soldering it.
On the underside of the FPGA there is a pad which must be connected to ground. A hole has been left in the PCB underneath the FPGA to facilitate this.
It is not complete yet I just got the board finished tonight. I have some test to do on it and some files to write and tidy up.
Frank
Hedghog II is mainly in response to all the recent trouble with the EP2C5 FPGA boards. For the most part it is the Same as Hedghog but with a few changes.
What's new in Hedghog II?
The biggest difference is the FPGA board is dispensed with. Now all the components are mounted on a single PCB.
The FPGA is changed to a more modern EP4CE6E22C8N.
The R2R DAC is changed from 9 bit to 10 bit.
It now can be used in modulator only mode.
The video out socked is moved to the rear panel and an extra toggle switch is added to the front panel.
The DIP switch is now a 6 pole type.
It has a test mode that drives the Test card from the 50 MHz clock. This will allow the 405 side of the FPGA to be tested without the video clock been required and so should help to identify video decoder problems.
There are some circuit changes.
A 50 MHz oscillator feeds the FPGA. From this the FPGA then generates all the other clocks. This includes a 14.31818 MHz clock for the video decoder which previously required it's own 14.31818 MHz crystal.
The pull-up resistors for the switches have been removed and it now uses the weak pull-up's provided by the FPGA.
The unused section of the video amplifier chip is now used together with a analogue switch to enable it to be used in modulator only mode.
To provide all the required power rails there are now 5 voltage regulators 5V, 3.3V, 2.5V, 1.8V and 1.2V.
It still fits on a double sided PCB of the same dimensions as the Hedghog PCB and so will fit the same cases.
Even though the EP4CE6E is a more modern FPGA with more resources on it that the EP2C5, it cost less.
The FPGA flash memory recommended for use with the EP4CE6E is the EPCS16SI8N. I have used the IS25LP016D-JNLE-TR which is pin for pin compatible and is a fraction of the cost.
The FPGA might look intermediating to solder but the pin pitch is the same as the video decoder. So if you are able to solder the video decoder there is no reason why you cant solder the FPGA, it just takes a little longer. In fact the I find FPGA easier to position because it is larger and because of it's size it is easy to place tape across it to hold it in place while soldering it.
On the underside of the FPGA there is a pad which must be connected to ground. A hole has been left in the PCB underneath the FPGA to facilitate this.
It is not complete yet I just got the board finished tonight. I have some test to do on it and some files to write and tidy up.
Frank
