====== TimeHat Overview ======
Pi HAT (hardware attached on top) for timekeeping applications.

Architecture:

  * GPS module with UART and PPS on 3v3 TTL
  * Maxim DS3231SN RTC module on i2c


===== Version 0.01 =====
Version 0.01 is what I already have made: COTS modules assembled on protoboard. 

No additional modules will be built.

{{:vault:screen_shot_2021-01-22_at_8.43.09_am.png?nolink&300|}}{{:vault:screen_shot_2021-01-22_at_8.43.19_am.png?nolink&400|}}
===== Version 0.1 =====
The 0.1 version will be a custom PCB with COTS modules.

Fifteen modules will be built. (Maybe 20, I ordered 20 PCBs)

|                  ^ Part                      ^ Link                                          ^ # Ordered  ^ Unit Cost  ^ Bulk Cost  ^ Misc                       ^
|                  | uBlox MAX-M8Q w/ antenna  | https://www.ebay.com/itm/264461410997         |            | $15.56     | $311.20    | $7.53 for GPS alone        |
|                  | DS3132 Module             | https://www.amazon.com/gp/product/B082VL4GM6  | 20         | $1.78      | 35.96      | (5 for $8.99)              |
|                  | CR2032                    | https://www.amazon.com/gp/product/B008XBK7PG  | 20         | $0.44      | $8.75      | (Pricing for 20)           |
|                  | M3 6mm Screws             | https://www.amazon.com/gp/product/B012TE12CY  | 60         | $0.67      | $10.01     | Bought 60, boards need 4   |
|                  | M3 11mm Standoff          | https://www.amazon.com/gp/product/B07D3Q9YDX  | 100        | $0.39      | $9.69      | Bought 100, boards need 4  |
|                  | 2x20 Pin Female Header    | https://www.amazon.com/gp/product/B07DNHS2SJ  | 20         | $0.94      | $18.76     |                            |
|                  | PCBs                      | https://jlcpcb.com/order                      | 20         | $1.28      | $25.50     |                            |
| Unit Cost        |                           |                                               |            | $21.06     |            |                            |
| Total Cost (15)  |                           |                                               |            |            | $419.87    |                            |


Part notes:

DS3231SN module dimensions: 21mm wide, 38mm long

MAX-M8Q module dimensions: 24mm wide, 29mm long (SMA conn adds 10mm)

Board Design:

{{:vault:screen_shot_2021-01-22_at_7.57.21_pm.png?nolink|}}
===== Version 1 =====
The first "real" version will be a custom PCB with the GPS module and DS3231 mounted directly to it, no intermediary parts.